GC19-6200-1 File No. S370/4300-20

Program Product GC19-6200-1 File No. S370/4300-20

IBM Virtual Machine/ System Product: Program Product Introduction

Program Number 5664-167

Release 2

-----~- - i::~~ Second Edition (April 1982)

This edition, GC19-6200-1, is a reV1S10n of GC19-6200-0. It applies to the IBft Virtual ~achine/System Product (5664-167) until otherwise indicated in new editions or ~echnical Newsletters. Changes are continually made to the information contained herein; before using this publication in connection with the operaticn of IBft systems, consult the IB~ 2:i2tem/370 and .!!300 f!:~.§§£!§ Bibli.£g~, GC20-0001, for the editions that are applicable and current.

For a list of changes, see page iii. Technical changes or additions to the text cr illustrations are indicated by a vertical bar to the left of the change.

It is possible that this material may contain reference to, or information about, IB~ products (machines and programs), programming, or services that are not announced in your country. Such references or information must not be construed to mean that lEft intends to announce such IB~ products, programming, or services in your country. Publications are not stocked at the address given below; requests for IB~ publications should be made to your IBft representative or to the IB~ branch office serving your locality.

A form for reader's comments is provided at the back of this publication. If the torm has been removed, comments may be addressed to IB~ Corporation, Programming Publications, Department G60, P.O. Box 6, Endicott, New York, U.S.A. 13760. IBM may use or distribute any of the information you supply in any way it believes appropriate without incurring any obligation whatever. Iou may, of course, continue to use the information you supply.

@ Copyright International Business ~achines corporation 1980, 1982 Summary of Amendments

summary of Amendments for VM/SP Release 2

This revision includes changes for: • IBM 3375 Direct Access storage • Trace Table Recording Facility

It also includes minor technical and editorial changes.

Summary of Amendments iii iv IBM VM/SP Introduction Preface

This publication introduces and describes f~ands (Qeneral Use~), SX20-4401 the IB~ Virtual ~achine/System Product (reference card) (V~/SP) • The subjects described in this book are: control Program (CP) , f~ands {other than conversationa1 Monitor System (CMS), remote SX20-4402 communications and interactive (reference card) problem control. CP Command ].§fere.!!£..g !~ Q~~ Users, This publication contains five sections SC19-6211 and two appendixes: EXE£ l Reference, SC24-5219 • "Introduction" describes VM/SP, virtual machines, and their applications. .ayst.§.!!! Product Edi!2~ SC24-5220 • "Control Program" describes how the VM/SP control program manages the resources of the real computing system. It also describes the automated operator support.

• "Conversational ~onitor system" describes the facilities of ~S: problem Operating .a.ystems in solving and program development GC19-6212 capabilities for interactive users.

• "Remote Spooling Communications" briefly describes the functions provided with a remote spooling network.

• "Interactive Problem Control Systems" Quic~ GUi£.§ !~ ~~, SX20-4400 briefly describes the functions provided (pocket reference) by systems that generate and catalogue system malfunctions.

• "Appendix A: VM/SP Publication-to­ Audience Relationship" Terminal User's Guid~, GC19-6206 • "Appendix B: VM/SP-Related publications for C~s Users and other Applications" Data Areas an£ Control Blo£~ Logic, 1'Y20-0891-- The reader must have a knowledge of data processing systems and definitions, and an understanding of virtual storage concepts. For information about virtual storage, see the student text publication Introduction to Virtua1 st2~~gg !B SystemL31Q, GR20-4260.

Information concerning the Device RELATED PUBLICATIONS Support Facilities program used with VM/SP to perform various inspection and initialization operations on direct IBM !!rtual Machine/System Product: access storage devices is found in:

~al Information Manyal, GC20-1838 CMS Command SC19-6209

£~ User's ~, SC19-6210

Preface v IBM !!rt]g,! Machine Facilit!Lill: The following communications provide information about the VTAM Communications Interactive Problem Control Network Application VM/VCNA) Program (IgcS) ]§.gr' s Guid~, GC20-1823- Product.

~ot~ ]EQoling Communications ~bsy~ IBM VM/Vg! Information, (RS£~) ]§.gr·s Guid~, GC20-1816 GC27-0501

System 1Qgic ~g Problem Determination IBM VM/VCNA Installation, Operation, and Guide Volume d RemO!~ Spooling Terminal Use, SC27-0502 Communications Subsyst~ ~CS) , SY20-0888 MISCELLANEOU S In order to use the CPEREP command, the following publications are required: A complete description of VM/SP !~ Virtual Machine/System prodyct OL1SEP restrictions is available in Vft/SP System and Error Recording Guide, SC19-6205 ~gg~ and Codes and VM/SP Plannil,tq and ~yst~ Generation.

Figure 1 is an overview of the Vft/SP library, and supplemental support, with the publications grouped according to their The first publication provides general probable users. information on usage and detailed information on command operands applicable References in the text to titles of only to VM/SP. The second publication related VM/SP and VM/370 publications are provides detailed information on the given in abbreviated form. operands that are common to OS/VS, nOS/VSE, and VM/370 as well as VM/SP. Unless otherwise noted, the term VSE refers to the combination of the DOS/VSE Program logic information describing the system ,control program and the VSE/Advanced interface between CMS and OS/VS EREP, and Functions program product. describing OS/VS EREP, is contained in the following: In certain cases, the term, DOS, is still used as a generic term. For example, IBM Virtual Machine/System Product disk packs initialized for use ,with VSE or ~~!£g Routines Progr~ Logie, LI20-0890 any predecessor DOS or DOS/VS system may be referred to as DOS disks. OS/VS, 1!QS/VSE, VM/37Q Envi!.Q1!~ta! Recording, Editing, gnd Printing (~REP) The DOS-like simulation environment Rrog£~m Logi£, SY28-0773 provided under the CftS component of VM/SP, continues to be referred to as CMS/DOS. In addition, all EREP messages are contained in the OS/VS, DOS/VSE, VM/37Q Environmental Recording, Editi~g, ~~ grinting (EREP) ~§Sges, GC38-1045.

vi IBM VM/SP Introduction Publications that support VM/SP as used in conjunction with VM/370 Release 6

VM/SP Licensed VM/SP General Information Program Spciflcatlons Manual ~ GC20-1842 (36) GC20-1838 (00) System Programming Support ..... ,.,., ... "., .. ~,I::,:,

Device Support VM/SP Library Guide VM/SP Planning and and Master Index VM/SP Introduction Note: The numbers given in Facilities User's r+-- parentheses represent System Generation Guide Guide and Aeference GC19-6207 (20) GC19-6200 (20) the Subject Code. SC19-6201 (34) GC35-oo33 (30) II II

VM/SP Terminal User's VM/SP Operating Systems VM/SP OLTSEP and Guide in a Virtual Machine Error Recording Guide GC19-6206 (40) GC19-6212 (34) SC19-6205 (37) Operations fJ D VM/SP System Logic and VM/SP System Messages VM/SP CP Command VM/SP System Reference for General VM/SP Operator's Guide Problem Determination and Codes ..-- 's Guide Guide Volue 1 (CP) Users SC19-6202 (40) SC19-6204 (40) SC19-6203 (36) SC19-6211 (36) LY20-0892 (36)

• ",:",:,.,. ..,,::,', .... ::: .... : . , :,,:..::: ~ CMS User VM/SP System Logic and II Problem Determination Guide Volume 2 (eMS) EAEP Messeges VM/SP CMS Primer LY20-0893 (39) GC38-1045 (40) SC24-S236 (39) i t :.,',:::: .. ,...... ,.. ,.:'::.,.,:.,.:. '.""':'. .:~ VM/SP Data Areas and II Control Block Logic LY20-0891 (36) VM/SP CMS User's Guide VM/SP CMS Command VM/SP Quick Guide for f---... and Reference Users SC19-6210 (39) (36) A uxiliary Support SC19-6209 (39) SX20-4400 t II

VM/SP Service Routines a J lEI ~~ Program Logic ~ : VM/370 Remote Spooling (37) OSIVS and VM/370 OSIVS, DOSIVS, VM/370 LY20-0890 Communications VM/SP Commands Assembler Programmer's Assembler Language (General User) Susbsystem User's Guiile Guide I~ GC33-4010 (~1I SX20-4401 (36) GC20-1816 (30) GC33-4021 (21) ( (, .::' . ':."". , ... ,.... .: II OSIVS and VM/370 II ..: Assembler Program Logic SY33-8041 (211 VM/370 System Logic and VM/SP System Product VM/SP Commands Problem Determination Editor User's Guide .. '. (Other than General Use) Guide Volume 3 (ASCS) SC24-S220 (39) SX20-4402 (36) .:':.... :,:':.. :,',."., .. : SY20-0888 (36) :.: II II VM/370 Interactive VM/SP System Product VM/SP SP Editor Environmental Recording, Problem Control System Editor Command and Command Language Editing, and Printing OPCS) User's Guide Macro Reference Reference Summary (EREP) Program GC20-1823 (37) SC24-5221 (39) SX24-S122 (36) GC28-0772 (37)

:~: II

VM/SP EXEC 2 Language Environmental Recording, VM/SP EXEC 2 Reference Reference Summary Editing, and Printing (EREP) Program Logic SC24-S219 (36) SX24-S124 (36) SY28-0773 (37)

':". ,.""".".".i Legend: .. For SNA terminal users, the prerequisite publication is; VMNCNA Installtion, Operations, and Terminel Use, Order Number SC27-0S02. B All users of virtual machine must use the VM/SP System Messages and Codes publication. II Contains information on VM/EAEP support. EREP Release 3 is recommended for use with VM/SP Release 2. II VM/370 Release 6 components. However, the IPCS Extension Program Product (S748-SA 1) and the RSCS Networking Program Product (S748-XP1) are recommended for use with VM/SP.

Ellf you want all three of the Reference Summary publications, use SBOF 3820 when ordering.

Figure 1. Virtual !achine/System Product Library, and Related Publications

Preface vii viii IB~ V~/SP Introduction Contents

INTRODUCTION • • • • • • • • • • • 1 paging and Page Migration. A • .11 VM/SP - Its Composition ••••• • 1 Virtual Storage Preservation • •• 18 Control Program •••••••• • 1 Operating Sjstem ••••• .18 Conversational Monitor system. • 1 Segments • • • • • • • • • .19 Remote Spooling Communications Named Systems. • • • • • • • • • • • • 19 subsystem • • • • • • • • • • • 1 Protected Named Systems •• .19 Interactive Problem Control system • • 1 Unprotected Named Systems. .19 The Virtual Machine. • • • • • • • • 2 Virtual Machine I/O Management .20 Virtual Storage. • • • • • 3 Virtual Disks. • • • • • • • • .20 Virtual Processor~ • • • • • 4 Channel. • • • • • • • • • • • .21 Virtual System Console • • 4 Virtual Machine Channel Mode Virtual I/O Devices. • 5 Selection • • • • .21 Logical Devices. • • • • • 5 DIAGNOSE Interface .21 Dedicated Devices. • • • • 5· Spooling Unit Record I/O .21 Virtual Disks. • • • • • • • • • • • • 6 Input Spool Files. .21 Virtual Unit Record Devices. • • 6 Output Spool Files .22 Virtual Transmission Control Units Adding and Transferring Files. • ••• 22 (Virtual Lines) • • • • • • • • • • • 6 Spooling Virtual Console 1/0 • • .22 Virtual Channel-to-Channel Adapter • • 1 Remote Spooling •• .22 VM/SP's User Directory •••••••• • 1 CP Commands. • • • • .23 LOGON Procedure. • • • • • • • • • • • 1 privilege Classes. • • • • .23 LOGON/AUTOLOG and LINK Journaling. • • B General Users. • • • • .24 Virtual Machine Operating Systems. • B Other Users •••••• .24 supported operating Systems. • • B VM/SP Attached Processor and Other Programs and Systems • • 9 Multiprocessor Support. • .24 VM/SP Applications • • •• • 9 Attached Processor support .24 system Programming • • • • • • • 9 Multiprocessor support • • .24 Application Programming ••••••• • 9 Virtual Machine Communication Facility .24 Operations • • • • • • • • • • • • • • 9 Inter-User Communication Vehicle • .25 Performance and Performance Options. • .10 programmable Operator Support. • • •• 25 Virtual Machine Assist • • • • • .11 Trace Table Recording Facility • .25 Extended control-program Support •• • 11 Locked Pages • • • • • • ~ 11 CONVERSATIONAL MONITOR SYSTEM. .21 Queue Drop Elimination • .11 CMS Configuration. • ~ • .27 Reserved Page Frames .11 CMS Pile System. • • • • .27 Virtual=Real • • • .11 User Disks • • • • • • • •• 28 priority Option ••••• • 12 File Identification •• • .28 Favored Execution. • • • .12 File Structure • • • • • •• 29 Affinity •••••••• .12 Initialization and DumE Restore. .29 Nondisruptive Transition (ND!) '10 and CftS Command Language • • • • • • .29 From Native Mode •••• .12 Program Development and Execution. .30 Single Processor Mode •• .12 Program Compilation and Execution Shadow Table Maintenance SUFPort • 12 Commands. • • • • • • .30 vn/vs Handshaking •••••••• .13 Language Processors. • • ,. • .30 VM/SP System/310 Extended Support. • • 13 Integrated Emulators • .30 Performance Measurement and Analysis • • 13 The CMS Editors. • .31 Error Recording and Analysis • • • 13 SCRIPT/VS. • ••••• .31 Other System Features ••••• .14 Centrol Commands • • • .31 Virtual Machine Accounting • • • • • • 14 CMS Tape Label processing. .31 Saved Systems ••••••• • 14 Alternating Cperating Systems • .31 Shared Systems • • • • • • .14 Detugging Facilities • • • • • • ••• 32 Discontiguous Saved Segments • .14 CMS Batch Facility • • • • • .32 Shared Segment Protection ••• .14 ~Virtual Machine Communication REMOTE SPOOLING COMMUNICATIONS. • .33 Facility ••••••••••• .15 --Inter-User Communication Vehicle .15 INTERACTIVE PROBLEM CONTROL SYSTEMS ••• 35 Programmable Operator Support. .15 Trace Table Recording Facility • .15 APPENDIX A: VM/SP AODIENCE-TO-PUBLICATION RELAT~ONSHIP •• 37 CONTROL PROGRAM. • • • • • • • • .11 Virtual Machine Time Management. .11 APPENDIX B: RELATED PUBLICATIONS FOR Virtual Machine Storage Management .11 CMS USERS AND OTHER APPLICATIONS •••• 41

Contents ix INDEX •••••••••••••••••• q5

FIGURES

Figure 1. Virtual ~achinE/System ligure 6. Virtual Machines Running Product Library, and Concurrent Production,

Related Publicaticns~ •• 4 ••• vii Development, and Testing~ •••• 10 Figure 2. Simultaneous Operations Figure 7. CP Privilege Class of Virtual ~achines •••••••••• 3 Descriptions ••••••••••••••••• 23 Figure 3. Real Disk Containing Figure 84 Sample CMS Configuration ••••• 28 ~inidisks •••••••••••••••••• ~.6 Figure 9. C!S File Identification •••••• 28 Figure q. Logging onto V~/SP and Figure 10. Relationship Among Virtual Loading CKS •••••••••••••••••• 8 Machine Users, Remote Stations Figure 5. Virtual ~achinE Operating and ep's Spool System •••••••• 3q Systems •••••••••••••••••••••• 8

x IBK V~/SP Introduction Introduction

Virtual Machine/System Product (VM/SP) CONTROL PROGRAM control program that manages the resources of an IBM System/370, or Q300, 3081, or 303x system complex in such a way that The control program (CP) executes in a real multiple users have a functional simulation machine controlling the resources of that of a computing system (a virtual machine) machine. CP is the vehicle that is used to at their disposal. create concurrent virtual machines. That is, the virtual machine runs as if it .were a real machine simulating both hardware and software resources qf the CONVERSATIONAL MONITOR SYSTEM system. These simulated resources can be shared either with other virtual machines or alternately allocated to each machine The conversational monitor system (CMS) is for a specified time. Furthermore, virtual a single-user designed to machines can run the same or different operate in a virtual machine. CMS Frovides operating systems simultaneously:--~hUs: a wide range of general-purpose, the individual user can create and adapt conversational time sharing functions. hi§ virtual machine to meet his own special needs.

REMOTE SPOOLING COMMUNICATIONS SUBSYS~EM VM /SP -Its Composition The Remote Spooling Communication Subsystem {RSCS)l, a VM/370 Release 6 component, is a VM/SP consists of four components: Control single-user operating system that runs Program (CP), Conversational Monitor system under CP. RSCS executes in one or more (CMS), Remote spooling Communications virtual machines and transfers data between Subsystem (RSCS), and Interactive Problem virtual machines and remote users. Control system (IPCS). Each of these components controls its unique part of the system. Together, these components Frovide the virtual machine with time sharing, INTERACTIVE PROBLEM CONTROL SYSTEM remote spooling, and problem repcrting for system/370 architecture uniprocessor, attached processor, and multiprocessor The Interactive Problem Control System systems. In publications, this collective (IPCS)l, a VM/370 Release 6 component, is a package, that is, CP, CMS, RSCS and IPCS, group of commands and controls that execute is referred to as VM/SP. under CMS to provide problem analysis and management facilities. IPCS standardizes The components RSCS and IPCS are the process of reporting problems and technically at a Release 6 level of the includes a method for identifying duplicate product. They do not contain new function Froblems within the system. It also to be supportive of the new function provides the user with the capability of provided in CP and CMS. However, there are viewing and diagnosing CP abend dumps program product counterparts to ESCS and through the virtual machine's operator's IPCS that have been technically advanced to console. work with new function provided in VM/SP.

These recommended program Froducts are: • Remote Spooling Communications sutsystem (R SCS) Networking, program number 5748-XP1 lNeither the RSCS or IPCS components of • Interactive Problem Control system VM/370 Release 6 have been functionally Extension, program number 5748-SA1 enhanced to be compatible with all of the functions Frovided in VM/SP. IBM recommends the use of the RSCS-Networking Program Product as well as the IPCS Extension Program Product. Both program products have been updated to sUPFort the functions of VM/SP.

Introduction 1 The Virtual Machine Figure 2. shows three virtual machines executing concurrently under CP on an IBM System/370 model 138, with 1024K of real A virtual machine is functionally storage. One machine is doing production equivalent to a real system. It has work under the current release of DOS and simulated hardware and software resources the other two virtual machines are that operate in a real under CP. executing CMS: one virtual CMS machine is Each virtual machine is defined in the available for each of two seFarate VM/SP directory; the directory describes conversational users. its simulated storage, I/O devices, and console.

2 IBM VM/SP Introduction VIRTl

Model 138

Operator Console

VIRT3 VIRT2

DOS 768K Virtual Storage

A real system reader is not a requirement for VM/SP but may be essential for an installation's program application.

Figure 2. Simultaneous Operations of.Virtual ~achines

Multiple virtual machines permit several • A conversion test from one operating systems to execute concurrently. Thus, system to another, such as from DOS/VSE production work may be run in one cr more to as/VS1 virtual machines while ether virtual machines are executing:

• A terminal-oriented conversational system VIRTUAL STORAGE

• A remote spooling subsystem, which transmits bulk data to and from remote A virtual storage system can simulate real locations storagE within a range of from 8K (8192) bytes to 16 megabytes (the maximum virtual • A back-release system that executes storage size). The virtual storage for application programs below the current each virtual machine is defined in the service level of the production system V~/SF directory.

• A current-release system with new Virtual storage extends beyond the size program temporary fixes (PTFs) applied of real storage and is not limited by the amount of real storage. It is highly • A new release or option that needs to be probable for the combined virtual storage generated and tested of several virtual machines to be greater than the real storage.

Introduction 3 Virtual storage can be managed and only reguire use of a hardcopy keyboard protected through segmentation. Each terminal. For more complex operations a segment is 64K, and there are from 1 to 256 more sophisticated device such as a segments depending on the size of virtual multicolor display terminal may be storage. required. For a list of the terminals VM/SP supports and their features refer to As a storage protection feature for all VM/SP ~lanniBg and System Generation Guide. virtual machines, page and segment tables are accessible only to CP. Generally, one The list of real terminal devices virtual machine cannot access or alter the supported for VM/SP virtual machine console virtual storage of another virtual machine; activity is extensive. This list includes however, mutually consenting users may display and hardcopy devices that adhere to read-only virtual storage and traditional local and teleprocessing line read-write virtual storage. protocols as well as other protocols supported by System Network Architecture Refer to the "Control program" section (SNA). SNA contains advanced communication of this publication for more information on protocols that are used with unique devices paging and storage management. that support it. An SNA virtual machine console can only be used in VM/SP through the use of another virtual machine, a service machine, that is running an VIRTUAL PROCESSOR application supportive of SNA terminals. The application. VM/VTAM Communications Network Application (VCNA) Program Product. CP provides each virtual machine with a maintains a dialogue with the console single virtual processor to execute services of CP through function in CP instructions and rece1ve interruFtions. called SNA CCS (Console Communication Actually, this virtual processor is the Services). The SNA Console Communications shared use of the real processor. CP Services (SNA CC5) provides the necessary simulates the privileged instructions, and interface between the existing CP system's the real processor executes the console services and the VM/VTAM nonprivileged instructions. Communications Network Application (VM/VCNA). See the publication, VM/SP The virtual processor provided in the system Programmer's Guide, for more virtual machine is a uniprocessor (one information on the SNA Console processor) simulation. Attached processor Communications Services component of CP. and multiprocessor simulation is not See the VM/VCHA publications listed in the supported in the virtual machine Preface for information on using SNA environment regardless of the terminals. installation's computer complex on which VM/SP is loaded.

VIRTUAL SYSTEM CONSOLE Traditionally, one real display terminal is used as a terminal console for one virtual The virtual machine system console has machine. Facilities exist in VM/SP where three major communication functions. console input and output information from First, to communicate to CP (the control multiple disconnected virtual machines can program portion of VM/SP) so that CP can be directed to one virtual machine's real provide to the virtual machine simulations terminal. of functions that are performed on r~al system consoles. Examples of this function A virtual machine is "disconnected" by are: IPL, START, STORE, and DISPLAY. detaching its assigned supporting terminal second, to provide the virtual machine user console. This is done by CP command. a means of dynamically altering sFecific Note. disconnecting the console does not attributes of a virtual machine; examFles negate current virtual machine processing. of attributes that may be altered are storage size, virtual machine operational This facility, the Single Console control parameters and performance options. Facility of VM/SP, uses directory supplied Third,' to Frovide a means of communicating values to direct any console activity from with the application program that is the disconnected virtual machine to another running in the virtual machine. To virtual machine's console. accomplish these functions requires a real terminal device. To handle simple This facility is helpful when requirements of C? and a CMS program observations of the interactions of two compile application, the virtual system may critical virtual machines can best be

4 IB~ VM/SP Introduction served by one console. In anotheI instIumental in creating it. Or the situation, where the console I/O activity logical device can be created for use by of some service machines is slight, it anot~~ virtual machine or another host would te economically feasible to have system. For more information on logical their combined activity consolidated onto device support, see the YM/SP System one user's display terminal. Programmer's Guid~. The VM Pass-Through Program Product (5748-RC1) is an example of one program that uses VM/SP's Logical Device Support Facility. Virtual I/O Devices

The virtual machine SUppOIts the same DEDICATED DEVICES devices as a real machine: it is the virtual machine, not CP, that contIols them. ~he I/O configuration must be Devices with a one-to-one correspondence defined by the user in the CP's user between real and virtual aIe referred to as directory entries. However, additional I/O dedicated devices. Tape devices are always requirements can be met dynamically by the dedicated. The user can dedicate disks, user via CP commands. terminals, and unit record devices to a virtual machine to improve the performance The user also has the option cf of that virtual machine. The 3800 assigning different addresses to his high-speed printer is also supported as a virtual devices, or using those of the Ieal dedicated device. devices. In either case, CP conveIts the virtual address to its real counterpart and When a device is dedicated to a virtual performs any necessary data translation. machine, that device is completely In addition, VM/SP allows the same virtual controlled by the virtual machine. address to be used by multiple users. Dedicated devices can be assigned dynamically by CP commands, assigned at VM/SP supports several types of logon time by directory control statements, virtual-to-real device mappings: or established by dial-up connections to virtual 270x or 370x telecommunications • Logical devices (Logical Device Support control units or virtual lines. Dedicated Facility) devices are also useful when operating devices that, while available to the • Dedicated devices System/370, are not supported by CP.

• Virtual disks (minidisks) • Virtual unit record devices • Virtual transmission control units (virtual lines) The 3850 Mass Storage system (HSS) can be dedicated to as many as four virtual • Channel-to-channel adapters machines running on VM/SP. The mass storage control (MSC) in the 3851 Hass Storage Facility (MSF) accepts reguests for data from one to four System/370 LOGICAL DEVICES processors. Each of the connections can be attached either to a different processor or to a different virtual machine. Other One form of virtual device is the logical non-HSS virtual machines can run device. The logical device is a product of concurrently. the Logical Device Support facility of CP. Virtual devices, as stated earlier, are With MSS, there are available to the generated via the user directory statements host processor as many as 192 DASD at the time of logon or afterwards by the addresses per DASD control unit. Up to 192 user via CP commands; whereas, the logical MSS volumes per control unit may be mounted device is created by CP by the execution of and online at any given time. Each of special code (DIAGNOSE) in a virtual these volumes may be accessed by a virtual machines program instruction stream. machine for the same purposes that a real 3330-1 is used. Any virtual machine may Generally, the virtual device belongs have access to all or part of an MSS volume exclusively to the virtual machine for just as though it were a real 3330-1, with which it was created, not so the logical one exception: CP may not use MSS volumes device; the logical device's affiliation for system residence, paging, or spooling. can be to the virtual machine that was

Introduction 5 When one or more of the MSCs channel Often, the user's application program ports is attached to the VM/SP system, the may require additional DASD for its volume REALID in Figure 3 can be a MSS processing needs. To this end, the user 3330V volume. The volume REAIIt will be can dynamically increase his virtual DASD dynamically mounted by the system whenever space allocations as the need arises. This minidisk MINI01, 3INI02, or MINI03 is DASD space, called Temporary or T-disk required by a virtual machine. storage, is acquired and relinquished from the users virtual machine as usage dictates. Information left on such disks at the end of a users session can be erased VIRTUAL DISKS by the system prior to T-disk space reassignment. Whether or not to erase T-disk space is an installations system Virtual disks are referred to as minidisks generation consideration (SYSCLR macro) and because more than one can be assigned to a is dependent on the data security real disk. These disks vary in size and requirements of the virtual machines it can be used by CMS, DOS, or as. For FEA services. devices, virtual disks are at least the size of one block and can be as large as the capacity of the real device. Figure 3 shows three minidisks that are assigned to VIRTUAL UNIT RECORD DEVICES one real 2319 disk volume. These virtual disks can belong to one virtual machine or three different machines. The user can Usually a real unit record device is not obtain, through VM/SP distribution, service kept busy constantly. Thus, the input and programs that create and change minidisKs. output of several virtual unit record devices can be handled by one real unit record device. When setting his Virtual Real configuration, the user can include as many Cylinder Cylinder virtual unit record devices as he feels he will need. CP controls these virtual Numbers o Numbers devices (as well as the real devices) and uses spooling to temporarily store input 1 and virtual output data on direct access storage space. CP then transfers input data to the appropriate virtual machine reader and allows a real printer or punch 49 to process output from the virtual device. Also spooled output frcm one virtual 50 machine can be directed to the spool input device of the same virtual machine or to 75 another virtual machine. Spooling is explained further under "Spooling Unit 76 Record I/O" in the "Control program" section of this publication. MINI03 126 202 VIRTUAL TRANSMISSION CONTROL UNITS (VIRTUAL LINES) Note~· Each minidisk starts at virtual cylinder zero. A virtual machine configuration can include a virtual transmission control unit (TCU). One real TCO can be used to simulate Figure 3. Real Disk containing Minidisks multiple virtual TCUs. A real TCU cannot be shared by concurrently operating virtual machines. The minidisk owner can ensure the However, by defining virtual transmission security of his disk by specifying a control units, a real---TCU can be password ... option to his read/write disk or concurrently shared by several virtual he can limit disk access to read-cnly. 10 machines. avoid updating conflicts, CP gives write access of a shared disk to one virtual machine at a time. However, the user can specifically request multiple access, if he so chooses.

6 IBM VM/SP Introduction VIRTUAL CHANNEL-TO-CHANNEL ADAPTER The Directory resides on the CP system residence DASD. The Directory is accessed by CP when a Frospective user attempts to The user can define a virtual gain access to a virtual machine. The channel-to-channel adapter (ClCA) with or process of ga~n~ng access to a virtual without a real eguivalent. If a real machine is called the logon process. If channel-to-channel adapter is dedicated to logon is successful, the user's virtual a virtual machine, that virtual machine can machine is built in real storage. The user communicate with a real comFuting system can then control it through virtual console other than its own real system. However, activity or other programming techniques. if it dces not exist, a virtual machine can only communicate with virtual machines in Many of the virtual machine's the same ccmputing system. characteristics defined in the user directory can be modified by commands. The There are alternatives to a virtual use of commands (invoked anytime after channel-to-channel adapter. One is the logon) allows the temporary modification of virtual machine communication facility certain virtual machine attributes for the (VMCP) ; another is the Inter-User duration of the current virtual machine Communication Vehicle (IUCV). Eoth of session. these facilities are described briefly in this section under the topic "Other system To change options on a more permanent Features." basis for a user's future virtual machine activity reguires intervention by administrative personnel to modify the directory and reinstall it on the system. VMjSP User Directory A more streamlined method of~directory updating is handled by the VM/Directory Critical to the virtual machine is its Maintenance Program Product, (Program definition in the VM/SP user directory. Number, 5748-XE4). This ~rogram allows the Each virtual machine is defined at user and administrative installation. The virtual machine personnel to share in the user directory directory entry, composed of control update process thus reducing much of the statements, defines the power and scope of administrative overhead. For details on each virtual machine. Some of the items this product, refer to the ~Directory that are defined for virtual machines are: Mainten~ Program Product General Info£~!i£B ~gByg!, GC20-1836. • The identification and password that must be used to gain access to a virtual machine LOGON PROCEDURE • The virtual storage size limitation • The commands that a user may use in To logon to VM/SP, a user enters (via a controlling the virtual machine (command keyboard terminal device that is connected privilege classes) to the VM/SP system) a valid userid and a password. This and other information in • The virtual machine's unit record the user's directory enables VM/SP to devices (that is, reader, printer, punch create a virtual machine that is tailored spool devices) to the individual user. • The permanent DASD assigned to the Figure 4 illustrates a logon procedure virtual machine for user "USER1". The user enters the userid. The system responds and then • The linkage reguirements needed to for the password to be en tered. (For access other virtual machines DASD security purposes this password is masked.) CP verifies the userid and password. The • Th~ special options that relate to the user is then notified by a CP response that virtual machine's performance and he is logged on. After successfully operational requirements logging on the system, the user may load any supported operating system and proceed. • The IUCV authorization requirements for users who require IUCV virtual machine to virtual machine dialogue.

Introduction 7 r- , SUPPORTED OPERATING SYSTEMS I I I /370 online I I logon USER1 I Figure 5 lists some of the operating I ENTER PASSWORD: I systems that can execute in virtual I I machines. I LOGON AT 11:03:18 ON WEDNESDAY 11/29/78 I I I I ipl cms I 1 I Batch or Single-User Interactive DOS Figure q. Logging onto VM/SP and Loading DOS/VS CMS DOS/VSE VSE/AF OS/PCP OS/MFT LOGON/AUTOLOG AND LINK JOURNALING OS/MVT OS/VS 1 OS/VS2 The integrity of a user's virtual machine OS-ASP and DASD space is directly related to the RSCS - Networking security of VM/SP. VM/SP has an installation option that, if used, forces Multiple-Access the masking of passwords that are used.in VM/370 virtual machine Logon and in the LASD ve/sp access process 1 • This masking of the of OS password prevents the inadvertent disclosure of the password to any Conversational unauthorized personnel. CMS

VM/SP can monitor and record igure 5~ Virtual Machine Operating unsuccessful logon attempts. In addition, systems VM/SP can also journal all successful and unsuccessful DASD linkage attemFts. If selected values With the exception of OS/PCP and eMS, (thresholds) are exceeded, an alert message these are all multiprogramming systems. is sent to the VM/SP system administrator However, when operating in a virtual by CP. machine, the user has the choice of running multiple partitions in one virtual machine (similar to stand-alone operation) or single partitions in multiple virtual Virtual Machine Operating Systems machines. When running multiple partitions in one virtual machine, multiprogramming and unit record spooling is done by both While the control program of VM/SP manages the operating system and VM/SP. When the concurrent execution of the virtual running Single partitions in multiple machines, it is also necessary to have an virtual machines, the need for multiple operating system manage the work flow virtual storages places a burden on within each virtual machine. Because each auxiliary storage. However, this can be virtual machine executes independently of alleviated by using shared systems. Shared other virtual machines, each one can use systems are discussed further on in this either a different operating system or section. different releases of the same cperating system.

Systems that can execute interactively by a single user include the conversational monitor system (CMS) and any operating system that can execute in a virtual lExempt from installation 0Ftion centrol machine. A time-sharing environment is are supported typewriter terminals that created when VM/SP creates multiple virtual are ~2! equipped with the print inhibit machines, each controlled by the same feature. For these devices, VM/SP types operating system. These systems operate masking characters over which the password concurrently with each other as well as is typed during the logon process. with other conversational or batch systems. 8 IBM VM/SP Introduction • Debugging from a hands-on console (a terminal device) as though on a dedicated real machine ~ultiple-access systems, such as MVS/SP, execute in one virtual machine and directly service many interactive terminals. ~o connect a terminal with the virtual APPLICATION PROGRAMMING machine, the user of a multi FIe-access system issues the DIAL command instead of the LOGON command. An interactive virtual machine environment provides these advantages for application Once his terminal is connected, the user programming: issues only the commands associated with the multiple-access system. For example, • Using the System Product Editor to the DIAL command connects the user's create source programs and data files terminal with a TSO system executing in a virtual machine. once his terminal is • using the CMS UPDATE command and the connected, the user communicates only with system product editor to maintain source that particular version of TSO. programs and data files

• Debugging from a terminal while under operating system control OTHER PROGRA"S AND SYSTE"S • Providing faster turnaround time, more test periods per day, and a shorter For information about other programs and development cycle systems that have been used under VM/SP, request information about IBM program • Designing application programs without products, Installed User Programs (IUPs), real storage limitations and Field Developed Programs (FDPs) from your local IB" branch office. • Defining minidisks and other virtual devices to design and test a slightly different or larger machine configuration before installing the VM/SP Applications hardware • Using SCRIPT/VS, a program product, for Using V"/SP, an installation can perform text preparation, to create and update its work more efficiently and easily. program specifications. Virtual machine applications aid ~n programming, operations, and interactive use. OPERA!IONS

SYSTE" FROGRAMMING An interactive virtual machine environment relieves problems of scheduling, sUFPort, and backup and expedites production. Some An interactive virtual machine environment of these operational advantages are: provides these advantages for system programming: • Training operators in a virtual machine that is isolated from production virtual • Reducing the amount of hands-on testing machines time on the real machine thereby reducing the requirements for off-shift • providing a shorter training period testing • Defining a virtual machine and its • Testing new or modified SVC routines in devices as backup to another real a virtual machine machine

• Applying and testing PTFs on a virtual • Running different types of work machine concurrently on a single real machine

• Generating and testing in a virtual • Reducing the manual handling and machine either new independent component scheduling of user test periods by the releases (ICRS) or new releases of an operations staff -- users run their own operating system virtual machines

Introduction 9 .--- 1 4341 Processor 1 2048K 1L-- ______----J I 1 l r- , 1 1 I 1 VP.!/SP 1 i I 1 1 I 1 L---- I 1 ..- I 1 1 1 VS1 Batch I 1 1 I 1 I 1 L , 1 I 1 1 I , 1 Ir-----., I 1--)1 VS1 Devl 1-)1 CMS 1 1 1 I 1 I 1 L--___~ , 1 r I 1 I Vl1/SP I 1 r-,----.... 1 1 ,------, 1->1 CMS I L----) 1 VS1 Devl 1 1 1 L ____..J I 1 1 ) 1 l' 1 , 1 Control 1 1 Unit ) 1 1 r-,----.... 1 1->1 CMS 1 • 1 1 I .---' L--, I J V Ii l , 1 r- ., II ,..- I 1 1----...... ITerminal) ITerminall I!erminall I~erminall L->I CMS L- I L- I L ____~ I

Figure 6. Virtual Machines Bunning Concurrent Production, Development, and Testing

• Executing many types of batch The backup system must include, but is applications with no change to the not limited to, the same type and number of program either in an individual virtual real devices as these virtual machines machine or in a virtual machine require. Also, the backuF system must have dedicated to executing programs in batch a sufficient number of direct access mode. storage drives so that the user volumes can be mounted. A possible combination of virtual machines in a VM/SP configuration is shown Because the virtual devices defined for in Figure 6. operating system testing is the virtual machines are not assigned to done concurrently with batch work and a specific real devices until execution time, variety cf conversational applications. the installation need not be concerned with device addresses.

Performance and Performance Options An installation using Vl"l/SP has more flexibility in using another System/370 ~he performance of any computing system is computing system for backup. Neither the judged by how efficiently it processes the same system/370 model nor the same amount work it has to do. The following factors of real storage have to be part of the influence the performance of a VM/SP backup system. system: the processor model used, the total

10 IBM VM/SP Introduction number of virtual machines executing, the EXTENDED CONTROL-PROGRAM SUPPORT type of operating systems being used in the virtual machines, the type of wcrk being done by each virtual machine, the type, Extended Control-program Support capacity, and number of primary paging (ECPS:VM/370) is a hardware function devices, the number of channels available, that is available on certain VM/SP the channel operating mode (block supported processors. This hardware assist multiplexer or selector), the amount of function, when used with the virtual real storage available, the use of machine assist function, further reduces alternate paths to I/O devices, and the use VM/SP real time to support virtual of Attached Processor (AP) support or machines, thus adding improved performance multiprocessor (MP) support. to the VM/SP system. In addition to the above considerations, VM/SP offers the following performance options to enhance the operating efficiency LOCKED PAGES of one or more virtual machines. !he performance options are: The system operator can, by use of a • Virtual machine assist command, lock virtual storage pages into • Extended Control-Program support real storage to increase the efficiency of (ECPS: VM/370) CP or selected virtual machines. 7his is • Locked pages done to eliminate paging activity on these • Queue drop elimination pages. • Reserved page frames • Virtual=real • priority QUEUE DROP ELIMINATION • Favored execution • Affinity • Nondisruptive Transition To and From The SE! QDROP userid OFF command can be Native Mode used to prevent a virtual machine's pages • Single Processor Mode from being scanned or flushed ·when the • Shadow Table Maintenance virtual machine is dropped from the active • VM/VS Handshaking queue because it is idle. Use of the SET • S/370 Extended Support QDROP userid OFF command can improve performance in cases where a cycle of gueue For detailed information ccncerning dropping and reactivation is repeatedly these performance options, refer to !M/S~ executed. Q£g£ato£!~ Guidg and VM/§~ Pla~1Dg gD~ System QengratiQ!! Quigg.

RESERVEt PAGE FRAMES VIRTUAL MACHINE ASSIST A more flexible approach than locked Fages is reserved page frames. The system When an operating system is run in a operator assigns a certain number of page virtual machine it is dispatched ty CP in frames to a specified virtual machine. The the prcblem state. All privileged pages are not locked into these page instructions issued by the operating system frames. pages can be paged out, but only cause program interrupts and CP must for other active pages of the same virtual simulate the desired effect cf the machine. operation. The virtual machine assist feature performs many of the privileged instruction simulation functions without the virtual machine leaving the problem VIRTUAL=REAL state. The result is a considerable reduction in overhead. Virtual machine assist may be considered a prerequisite to The virtual=Ieal option allows one selected running production jobs under an operating virtual machine to run totally within real system in ·a virtual machine. storage. This eliminates all' paging activity for this virtual machine (except The system operator enables or disables page 0). Use of this option reguires that the virtual machine assist via a command. a virtual=real area be allocated to real However, if the function has been enabled storage during the system generation for the system, the user has the choice of process. In addition, virtual machines setting it off for his machine, and later that are to use this area must have the setting it on again. virtual=real option specified in their user

Introduction 11 directory option statement. Note, only one SINGLE PROCESSOR ftODE virtual machine can use the virtual=real storage allocation at anyone time. The virtual=real option usually results in a Single processor mode improves the performance improvement for the selected throughput of OS/VS2 MVS attached processor virtual machine, however, it must be (AP) systems or tightly coupled understood that the dynamic paging area for mu~tiprocessing (MP) systems running under all other concurrently operating virtual V8/SP. To use single processor mode, MVS machines is reduced by the virtual=real must be running in the V=R virtual machine. area. When an MVS AP or MP system runs under V8/SP without single processor mode, MVS runs on only one processor. Running in PRIORITY OPTION V8/SP'S single processor mode, ftVS runs on two processors: MVS has exclusive use of one processor while VM/SP controls the The priority option affects the execution other processor. The VM/SP side of the of a particular virtual machine as compared multiprocessor configuration has among its with other virtual machines that have the virtual machines, a large V=R machine same characteristics. A priority value dedicated to the balance of the ftVS system. assigned to a virtual machine is used, in Single processor mode improves MVS combination with other factors, to throughput by running MVS on two processors influence the dispatching algorithm. The instead of one. For details on the lower the value, the greater the percentage operation of single processor mode, refer of processor time given the virtual to !~Ll~ QE~~at!Bg llste!§ in g jirtyal machine. Machine.

FAVORED EXECUTION SHADOW TABLE MAINTENANCE SUFPORT

The favored execution option can provide a In V8/SP, CP maintains tables that relate particular virtual machine an assured real storage allocations (first level percentage of real processor time. storage) to the virtual storage provided to the virtual machine (second level storage). The virtual machine's VS system (Extended-control mode) provides additional AFFINITY tables to control its own virtual storage (third level storage). CP maintains tables that map first level storage to third level Under normal attached processor mcde or storage for use by the real machine in its multiprocessor mode, either processor can paging operations; these tables are called handle the virtual machine execution. shadow tables. Maintaining shadow tables However, with the affinity capability, only constitutes a considerable amount of the specified processor will allew virtual overhead for CP. The Shadow Table machine execution. Maintenance support eliminates much of the overhead of shadow table maintenance in the following areas:

NONDISROPTIVE TRANSITION (NDT) TO AND lROM • Multiple shadow table support NATIVE [flODE • Selective invalidation • Shadow table bypass for V=R users • Shadow tatle bypass for V=V users Dynamic system control program (SCP) transition to or from native mode enables Briefly, maintaining multiple shadow an operator to dynamically switch an SCP tables relating to the multiple address from a guest V=R virtual machine spaces that are used by a guest operating environment to a stand-alone (or native) system reduces the need of shadow table environment and vice versa. There is no purge operations. VM/SP will dispatch the need to initial program load (IPL) the SCP proper shadow table when the virtual or VM/SP to make the switch. After the machine operating system dispatches a new transition of being switched to native address space. mode, the SCP can resume operations. For details on the operation of dynamic SCP The selective invalidation function transition to and from native mede, refer allows entries within the shadow tables to to the !!L~~ Operating ~yst~!§ in ~ Virtug! be selectively invalidated (rather than ~hin~. invalidating and purging the entire table)

12 IBft VM/SP Introduction when VM/SP steals or releases a page frem a • Providing a way to avoid a PCI virtual machine. (program-controlled interruption) in a BTAM autopoll CCW loop. Shadow table bypass for V=R users allows the elimination of the shadow tables and • Providing miscellaneous enhancements the associated CP overhead in maintaining when running under VM/SP. them. This is achieved because all the virtual machine pages are mapped directly to real pages with the exception of page O. VM/SP SYSTEM/310 EXTENDED SUPPORT Shadow table bypass for the V=V user also reduces CP overhead in maintaining the associated shadow tables. The address VM/SP supports the System/370 extended spaces in guest operating systems may have facili ty of the 3031, 3032,' and 3033 segments or pages which are mapped V=Ri processors. It also supports the also, guest systems may have common System/370 extended feature of the Model segments which are common between the 158 and 168 processors. The VM/SP support different address spaces. These areas can allows a virtual machine to make use of the be defined by CP command with the effect System/370 extension functions, provided that these areas become common in the the feature is installed. The functions shadow tables. This reduces CP overhead in provided by the System/370 extended feature maintaining the set or sets of shadow or facility include: tables for the virtual machine. • Low address protection • Common segment support • HVS assist operations VM/VS HANDSHAKING • Invalidate Page Table Entry (IPTE) instruction • Test Protection (TPROT) instruction. VM/VS handshaking is a communication path between CP and the following operating For more information on VM/SP support of systems running as virtual machines under System/370 extensions, refer to VH/SP VM/SP: lY2~~! prog£s~!~~~ Guig~. • DOS/VS Release 34 Advanced Punctions DOS/VS program product (S146-XE2) Performance Measurement and Analysis • DOS/VSE with VSE/AP program product (S746-XE8) The VH/SP control program has two commands • VS1 Release 4 and subsequent releases that cause CP to collect and display p~rformance related data. To improve their operation with VM/SF, the operating system and CP make each other The MONITOR command gathers data aware of mutual capabilities or relating to most aspects of system requirements. Systems generated to use performance and writes the data on tape or V~/VS handshaking may have the dual ability spool file. When the data is reduced, it to run both in a real machine and in a may indicate the conditions contributing to virtual machine. Virtual machine systems performance degradation. that have VM/VS handshaking can more realistically simulate the operation of The INDICATE command displays, at the their real machine. terminal, some key information about the system to show the current performance VM/VS handshaking consists of: conditions. INDICATE displays the system conditions existing at the time it is • Closing CP spool .files when jeb eutput issued. is complete. This allows VM/SP to immediately process these output files without operator intervention. Error Recording and Analysis • processing pseudo page faults. When the pseudo page fault handling portion of handshaking is active, one task can be Cperating systems that commonly run in dispatched while another is waiting for virtual machines write error records to the a page to be brought into real storage. error recording data sets. However, in a virtual machine CP intercepts the error, • Providing a nonpaging mode to eliminate and VM/SP records the error in its own duplicate paging. error recording area. Therefore, error

Introduction 13 records from all operating systems reside SHARED SYSTEMS in this one centralized error recording area. A saved systes can also share reentrant portions of its virtual storage among many concurrently operating virtual machines. Other System Features In a uniprocessor environment, regardless of the number of virtual VM/SP contains several other features that machines using the shared segments, only expand the capabilities of operating one copy of the pages in the shared segment systems running in virtual machines. They need ever occupy real storage and external are: page storage. In an attached processor or a multiprocessor environment, there will be • Virtual machine accounting one copy of the pagels) in the shared • Saved systems segment per processor. This reduces the • Shared systems total real stcrage and auxiliary storage • Discontiguous saved segments required. • Shared segment protection • Virtual machine communication facility The greater the number of virtual • Inter-User Communication Vehicle machines that are using a shared system, the greater the storage savings, and the greater the probability that the shared pagels) will be frequently referenced. VIRTUAL MACHINE ACCOUNTING Freguent1y referenced pages tend to remain in real storage, thereby reducing paging activity. Less paging activity increases VM/SP keeps track of a virtual machine's the efficiency of the processor. usage of system facilities and records accounting information whenever the use of some chargeable resource is terminated. VM/SP accounting information is spool file DISCONTIGUOUS SAVED SEGMENTS data. By using VM/SP system generation controls, this information can be directed to a virtual machine that specializes in Discontiguous saved segments (DCSS) are accounting transactions such as billing and similar in many ways to saved systems. resource analysis. options of punching DCSS must have been named, loaded,. and . this information via a real punch or saved as when saving a system; they must dumping this information to tape are also also be loaded at an address higher than available. the highest address of the virtual machine using it. DCSS can te logically attached by a SAVED SYSTEMS virtual machine whenever needed and detached when not needed. The CP instructions required to perform the When initially loading an operating system linkage must be part of the virtual into a virtual machine by device address, machine's operating system. VM/SP reads the resident nucleus into real storage and writes it back out to the Not~: Systems using DCSS cannot be loaded system paging device. Simultaneously it into the virtual=real area of VM/SP. An updates the virtual machine's paging attempt to do so results in an error tables. message. In addition, a system programmer can specify certain requirements to ensure the integrity of a virtual machine and to SHAREt SEGMENl PROTECTION successfully recover certain virtual machines. At system generation, the system programmer can specify that the virtual The mode of shared segment protection may machine contents of specified users (via a be specified at system generation time. system generation macro) be saved automatically on DASD if either VM/SP With shared segment protection, VM/SP terminates the virtual machine or if VM/SP protects the multiple users of shared itself is terminated. segments from any intentional or inadvertent alteration of the shared segment's code or data. Before CP selects a new user to be dispatched, it checks

1q IBM VM/SP Introduction whether or not the current virtual machine INTEE-USER COMMUNICATION VEHICLE has altered any pages in shared segments. If so, CP places the virtual machine in console function mode, returns the altered The inter-user communication vehicle (IUCV) page to free storage, and prepares a fresh defines a precise protocol for copy of the shared page for the remaining communication between virtual machines shared system users. operating under the same VM/SP system. In addition, it is possible for authorized Without shared segment Frotection virtual machines to communicate with specified for a named system, changes made console communication services portion of by a user to pages in shared segments of VM/SP's control program. Por more detail the system remain undetected by the VM/SP on the function provided by IUCV, refer to control program. All users of the the "Control program" section of this unprotected shared segment will see the publication. change. Installations choosing to run with unprotected shared segments should PROGBAM~ABLE OPEBATOB SUPPORT carefully evaluate these segments tc ensure that they contain read-only informaticn. The unprotected option for shared segments Programmable Operator allows operation of a [ will eliminate the overhead invclved in VM/SF system to be automated with scanning for changed pages in uDiFrocessor, I predefined procedure or controlled from a attached processor and multiFrocessor I,remo e VM/ st. For more information, systems, in switching page table pointers, I see the "Control program" section of this and in maintaining duplicate copies of I book. shared systems in an attached processor environment.

TRACE TABLE RECORDING FACILITY

VIRTUAL MACHINE COMMUNICATION FACIlITY The Trace Table Recording Facility provides Field Engineering and service personnel The virtual machine communication facility with the ability to create a synchronized (VMCF) allcws one virtual machine to collection of trace table data. A more communicate and exchange data with other detailed description can be found in the virtual machines operating under the same "Control Program" section of this manual. VM/SP system. A more detailed descripticn of VMCP can be found in the "Control ...... Program" section of this publicaticn:---

Introduction 15 16 IB~ VM/SP Introduction Control Program

This section describes briefly the major Virtual Machine Storage Management functiens provided by the centrel program portion of VM/SP. They are: Each virtual machine has storage associated • Virtual Machine Time Management with it; the amount of storage is defined • Virtual Machine Storage Management in the user directory. Each virtual • Virtual Machine I/O Management machine functions as if it has a large • Spool Management amount of real storage. However, each • Virtual Machine-to-Virtual Machine virtual machine's storage is created and Communication Management controlled by CP as virtual storage. The virtual machine's storage can be larger or Communications between virtual machines smaller than the storage of the real are handled by Virtual Machine machine. Communication Facility (VMCF) and the Inter-User Communication Vehicle (IUCV). The user directory entry contains two sizes for each virtual machine: its normal size and a maximum size. The normal size must be at least 8K (8192) bytes. The Virtual Machine Time Management maximum size must be no larger than 16 megabytes. Both sizes must be multiples of 4K (4096). When a user logs on, his Although virtual machines appear to their virtual machine storage size is the amount users to be executing instructions, it is of storage defined as the normal size. the real processor that is actually doing However, the user can temporarily redefine the work. his virtual sterage size to any value that is a multiple of 4K (4096) and not greater VM/SP uses a technigue called time than his virtual machine's maximum size. slicing so that one real processer appears to be mUltiple virtual processors. Each storage in the virtual machine is virtual machine periodically gains access logically divided into 64K (65,536) byte to the real processor for a small ameunt of areas called segments. These are further time, called a time slice. CP determines divided into 4K byte areas called pages. how frequently and for how much time a For each virtual machine, CP creates and virtual machine gains access to the real updates a set of segment and page tables to processor by examining the number of describe the virtual storage and to reflect console reguests, or terminal interrupts, the allocation of the virtual storage pages the virtual machine has issued during its to page frames in real storage. These past time slices. If the number is large, tables are used by the Dynamic Address CP defines the virtual machine as a Translation feature during virtual machine conversational user and assigns it the execution to locate the real storage smaller of two possible time slices. If addresses to which the virtual storage the number is small, the virtual machine is addresses actually refer. a nonconversational user and is assigned the larger time slice. CP gives conversational users more frequent access to the real processor for short time PAGING AND PAGE MIGRATION slices, while it gives nonconversational users larger time slices at less frequent intervals. The storage of the real System/370 is physically and logically divided into 4K CP allows a virtual machine to gain byte areas called page frames. When a page a~cess to the real processor only if the of virtual storage is brought into real virtual machine is not waiting for some storage, it fits exactly into a page frame. resource or activity, such as: Heavily used portions of VM/SP are kept • A page of storage to be loaded from in real storage. However, to optimize real auxiliary storage into real sterage storage use, pages, both CP and virtual machines, that indicate high paging • An input/output operation to be activity should be relegated to Faging translated, begun, or completed devices and facilities that have high access speeds; namely: the 2305 drum, DASD • A CP command to finish executing fixed-head area, and areas of DASD where

Control Program 17 the access travel time (mechanical seek real storage page frame until it is time) is minimized. Such areas on drum and actually needed for virtual machine DASD are preferred paging areas. Areas execution. No attempt is made by CP to beyond these designated areas are referred antiCipate what pages might be required by to as nonpreferred areas. The allocation a virtual machine. While a paging and grouping of preferred and nonpreferred operation is being performed for one areas are VM/SP system generation virtual machine, another virtual machine considerations. can te executing. paging operations are initiated and performed by CP and require The dynamics of CP's paging activity can no action by the virtual machine. saturate or fill the preferred and the nonpreferred DASD space; therefore, a page migration function of CP is used to move less active pages to nonpreferred DASD and VIRTUAL STORAGE PRESERVATION also to migrate pages that have increased paging activity fromnonpreferred tASD to preferred DASD locations. The system programmer can specify, at system generation time, that the virtual Page migration occurs automatically when machine contents of certain userids are to system threshold limits are attained. CP's be saved automatically if either the MIGRATE command can also be used to virtual machine is terminated by VM/SP, or initiate page migration. if VM/SP itself is abnormally terminated. The contents of these virtual machines are A page can be brought into any available saved on DASD space the VM/SP system page frame; the necessary relocation is programmer allocates. The user can restore done during program execution by CP using the saved virtual machine via the IPL dynamic address translation. ~he active command and then initiate normal recovery pages from all logged-on virtual machines procedures for the virtual machine. The and from the pageable routines cf VM/SP automatically saved virtual machine is made compete for available page frames. When available to only two previously specified the number of page frames availatle for userids. This is done in order to preserve allocation falls below a threshold value, the privacy and security of the virtual CP determines which virtual storage pages machine. The virtual machine's IPL is currently allocated to real stcrage are altered so that the saved virtual machine relatively inactive and initiates suitable can be loaded into either a V=R or a normal page-out operations for them. non V=R machine. Where multiple virtual machines are to be saved the order in which Inactive pages are stored on a direct to capture the contents of the VMS AVE access storage device. If an inactive page systems can be established by system is changed at some time during virtual generation macro values. machine execution, CP assigns it to a paging device, selecting the fastest paging device with available space. If the page is not changed, it remains allocated in its OPERA~ING SYSTEM original direct access location and is paged into real storage from there the next time the virtual machine refers to that The operating system controlling a virtual page. A virtual machine progran can use machine may execute in extended control the DIAGNOSE instruction to communicate to mode. This means that an operating system CP that the information from one cr more can create and control its own virtual specific pages of virtual storage is no storage, in addition to the virtual storage longer needed; CP then releases the areas it has which is controlled by CP. The of the paging device that were assigned to virtual machine operating systems that can hold the specified pages. do this are: OS/VS1, MVS, DOS/VS, DOS/VSE, VSE/AE, VM/370, and VM/SP. In the In areas where the preferred space is following example, as/VS1 is used to heavily used and page migration is unable illustrate how an operating system handles to identify unused pages on the preferred the virtual storage it creates, and how DASD space, the system will be switched to this is different from the virtual storage fair share allocation mode. When the that VM/SP creates for a virtual machine. demand lessens and the numter of active pages becomes less than the available OS/VS1 creates and controls a single preferred DASD space, tbe system will virtual storage. It creates and updates a switch back tc normal allocation mode. set of page and segment tables that relate this virtual storage to the virtual storage paging is done on demand by CP. ~his of the virtual machine. In VM/SF, "first means that a page of virtual storage is not level storage" refers to real storage, read (paged) from the paging device to a "second level storage" refers to virtual

18 IEM VM/SP Introduction machine storage, and "third level storage" A named system is attached to a virtual refers to the virtual storage created and machine at the addresses specified when the controlled by the virtual machine. ~hen system is defined by the systems OS/VS1 is executing, instructions and data programmer. Named systems may be attached from third level storage must be available within or beyond the extent of a virtual to the processor. Thus the real machine machine's defined storage. cannot use the page tables created by OS/VS1 nor the page tables created by CP. When it is defined, some segments of a The real machine must have a set of page named system may be designated as private. and segment tables that relate third level Each attached user gets a private copy of storage to first level storage. CP such segments initialized to the initial dynamically constructs and updates such contents of these segments. Thereafter, tables, called shadow tables. CP maintains each user may alter his private segments of shadow pages for any virtual machine the named system. There is only one copy running ~n EC mode. A single set is all of the shared segments of a named system in that is necessary for OS/VS1 or DOS/VS. real storage (in attached processor and multiprocessor systems there are two copies However, when VM/SP or VM/370 are used of protected shared segments). Sharing the as a virtual machine operating system, same segments results in reduced real multiple virtual storage systems can be storage requirements and reduced paging created. In this case, the shadow tables activity. The greater the degree of are maintained by the host CP whenever the sharing, the greater the real storage guest VM/SP or VM/370 passes centrel from savings and the greater the probability the one virtual machine to another. shared pages will be frequently referenced. Frequently referenced pages tend to remain in real storage thereby reducing Faging activity. Reduced paging activity frees SEGMENTS the processor for mor~ productive work.

Virtual machines can share one or more segments of virtual storage. ~he user has PROTECTED NAMED SYSTEMS the opticns of having shared segments:

• Statically defined and read-only VM/SP protects the multiple users of (protected) , Frotected named systems from any • Statically defined and read-write intentional or inadvertent alteration of the named system's code or data. Before CP dispatches a new user, it checks whether or not the previous virtual machine altered NAMED SYSTEMS any shared pages of a protected named system. If so, CP places the Frevious virtual machine in console function mode, statiC definition of shared segments occurs returns the altered page to free storage at CP system generation. Each such and then CP refreshes the contents of the collection of segments is called a named shared page from the original disk version. system. The system programmer defines a collection of segments (their contents and keys) as a named system. This also defines whether the named system is Frotected UNPRO~ECTED NAMED SYSTEMS (shared read-only), or unprotected (shared read-write). Thereafter users may attach or detach the named collection using a Unprotected named systems allow sharing DIAGNOSE code. If the segments constitute users to alter shared pages of the named a system control program (for examFle, system. All users of an unprotected named VM/SP), the user may attach it by issuing system see such changes although the the command "IPL system-name". changes are not reflected to the disk and so do not survive CP restarts or periods in CMS is an example of a named system. which the named system is not shared at The central piece of CMS is shared among all. users as a read-only (protected) named system which is invoked by the IPL command. Installations choosing to run with Other parts of CMS (for example, sUPFort unprotected named systems should carefully for VSAM, DOS) are separate protected named evaluate these systems to assure that they systems which are connected to virtual contain read-only information. The machines as needed via the Diagnose unprotected option eliminates the overhead interface code. of scanning all Fages of the named system at each dispatch. In attached processor or

Control Program 19 multiprocessor systems it eliminates the operation is transparent to the virtual duplication of pages of the named system in machine. However, if the virtual device is real memory. For a description of shared defined as a 3330V, no prefix is added to segments see the VM/SP System ~~~~~~~ the channel program and cylinder faults ~. must be processed by the virtual machine. During cylinder fault processing, CP designates the virtual machine as not Virtual Machine I/O Management executable. When the virtual machine gains control, CP gives it a suitable condition code (as on a real machine) to indicate the The virtual machine operating system is status of the Start I/O operation. In responsible for the operation of all addition, CP reflects to the virtual virtual devices associated with it. These machine the interrupts caused by the virtual devices may be defined in the use~ input/output operation for its directory entry of the virtual machine, or interpretation and processing. they may be attached to (or detached from) the virtual machine while it is logged on. Interrupts indicating that an MSS virtual devices may be dedicated, if they cylinder fault has occurred, and that a are assigned to a fully equivalent real cylinder fault has been resolved, are device; shared, if a minidisk is linked by passed to the virtual machine only if the more than one virtual machine; or spooled virtual device is defined as a 3330V. by CP to intermediate direct access storage.• If input/output errors occur, CP does not, as a general rule initiate error When any operating system executes in a recovery operations; these are the real machine, input/output operations are responsibility of the virtual machine initiated when a problem program requests operating system. Basic error recording the operating system to issue a start I/O is, however, provided by CP. For more instruction to a specific device. Device information on error processing, see the error recovery is handled by that system. VM/S1? QL~SEg !ind Err~ ReCordin£} Guide. In a virtual machine, guest operating systems can perform these same functions, The programs to be executed in a virtual but the device address specified and the machine (except a virtual=real machine) storage locations referred to are virtual. gene~ally must not include dynamically CP translates the virtual addresses to real modified channel programs. These and other addresses. restrictions that apply to virtual machines are discussed in the !~/SP Plann!~ and Because the virtual machine executes Sys!m!! Generation Guide. only in virtual (not real) supervisor state, CP gains control when the start I/O instruction is issued by the virtual machine operating system. CP copies into VIRTUAL DISKS its own work area the channel command list specified by the operating system, and pages into real storage all virtual storage Virtual disks, often called minidisks, can locations required for data transfer. The be shared by several virtual machines. specified pages are fixed in real storage Virtual disk sharing is specified in the until the input/output operation completes. user directory entry or by a user command. If a single channel command word specifies If the user issues the CP LINK command to a data area extending over multiple pages share a virtual disk, he must supply the of contiguous virtual storage, CP generates appropriate password before actual linkage channel programs that use channel indirect can be established. data addressing to handle noncontiguous page frames. If the virtual device is a A particular virtual machine may be minidisk, CP modifies any tASD sFace assigned read-only or read/write access to allocation to reflect the true lccation of a shared virtual disk. CP checks each the data. CP assigns the virtual device virtual machine input/output operation address to the real device and schedules an against the speCifications in the virtual actual input/output operation. machine configuration to ensure device integrity. When an I/O device is a Mass storage System (MSS) 3330V, but the virtual device Virtual disks may be defined for is defined as a 3330-1, CP places a prefix temporary use by a virtual machine. In on the actual channel program. This prefix that case, CP allocates real disk storage allows CP to determine when ·an MSS cylinder to the virtual machine until the virtual fault occurs and queue the I/O operation machine logs off or specifically detaches until the cylinder fault is resolved. ~his the temporary virtual disk.

20 IBM VM/SP Introduction CH.ANNEL DEFINE command or via the user directory entry for a virtual machine. A virtual machine may be assigned a dedicated channel, via·the ATTACH CHANNEL command. If a virtual machine is assigned DIAGNOSE INTERFACE a dedicated channel, it has that channel and all of its devices for its exclusive use. CP translates the virtual storage A virtual input/output operation by CP can locations specified in channel commands to be simplified if the virtual machine uses real locations and performs any necessary the DIAGNOSE interface. CMS was designed paging operations, but does not need to specifically for the virtual machine translate any device addresses. The environment, and uses this interface virtual devices on a dedicated channel must instead of the normal Start I/O instruction have direct, real equivalents (for example, for most of its input/output operations. minidisks are not allowed), and the virtual When the Diagnose interface is used, CP and real device addresses must be handles input/output error recovery identical. A channel dedicated to a operations. virtual machine cannot be used by any other virtual machine. Virtual machines may have Input/output operations initiated by CP a mixture of dedicated and nondedicated for its own purposes, for example, paging channels. and spooling, are performed directly and are not subject to the translation process described in the preceding paragraphs. VIRTUAL MACHINE CHANNEL HODE SELEC!ION Spooling Unit Record I/O Virtual machine SIO (Start I/O) operations are simulated by CP in three channel modes: byte multiplexer, selector, and block CP spooling facilities allow multiple multiplexer. virtual machines to share real unit record devices. Since virtual machines controlled Virtual byte multiplexer channel mode is by CMS ordinarily have low reguirements for reserved for I/O operations for devices unit record input/output, real device allocated to channel zero. sharing is advantageous, and is the standard mode of system operation. Selector channel mode, the default mode, is the mode of operation where only one I/O CP, not the virtual machine, controls task can be executing at one time. Another the unit record devices that are designated I/O task initiated to another device on the as spooled in the directory entry. When same channel will be held out with a busy the virtual machine issues a Start I/O condition until the first task completes. instruction to a spooled unit record Selector channel is the mode of operation device, CP intercepts the instruction and for any channel that has an attached modifies it. CP moves the data into channel-to-channel adapter (CTCA) , page-size records (that is, 4096-byte regardless of the selected channel mode blocks) on a VM/SP disk area that serves as setting. Because the CTCA is treated as a intermediate storage between the real unit shared control unit, it must be connected record device and the virtual machine. to a selector channel. Block multiplexer channel mode allows the virtual machine's operating system to INPUT SPOOL FILES overlap SIO requests to multiFle devices connected to the same channel. For a virtual machine in block multiplexer mode, Input spool files, that is, data available CP simulates a real block multiplexer at a virtual card reader, can be created operation. from real card decks. The real machine operator places the card deck in the input ~: CP simulation of block multiplexing hopper of the real card reader. The real does not reflect channel available card deck must be preceded by a USERID card interrupts to the user's virtual machine. that names the virtual machine to receive the card deck. The selection of block multiplexer channel mode or selector channel mode is InFut spool files can also be created by effective regardless of the real channel using a remote spooling work station on a devices on the System/370. lhe channel network. The operator at the remote work operating mode is selected via the CP station must place a card deck in the

Control Program 21 hopper of the remote card reader. This identifiers imbedded in the control card deck must be preceded by a USEBID card information associated with each closed that names the virtual machine that is spool file to control the ordering and controlling the spooling network and the transfer of the spool file. Spool file virtual machine that is'to receive the card identifiers are: file. In this way, cards at a remote location can be made available to any spoolid - A unique number (assigned by CP virtual machine. sequentially from 1 through 9900) that the system assigns when the spool file is created. The VM/SP control program prevents the reassignment of duplicate OUTPUT SPOOL FILES spool file identifiers.

§EQQ!ing £la§§ Dy user directory Output spool files are created on direct statement or by CP command, the user can access storage when the virtual machine assign a one character identifier to file operating system writes to a virtual punch group~ngs. These assignments can represent or printer. Real output is scheduled for a security categories, geographic regions, or real printer or punch, or fer remete priority classes. output, whenever a user logs off the system or issues a CP CLOSE (or SPOOL command with form number - A form number can be assigned the CLOSR operan~ command. by cp-Command for real spool output files. The form number is used in alerting the systems spooling operator of the output forms or card requirements of the ADDING AND TRANSFERRING FILES forthcoming output spool file.

If the direct access storage space assigned to spooling becomes full, spooling stops Spooling Virtual Console I/O and the virtual unit record devices appear to be not ready. The spooling operator must make additional spooling space CP allows the user to spool his virtual available. The spooling operator can purge machine's console input/output on disk, existing spool files or assign additional instead of, or in additicn to, having it direct access storage space for spool displayed at his terminal. The data files. As an alternative, the spooling spooled includes messages from or to the operator can dump spool files to tape for virtual machine operating system, CP later retrieval and processing. When spool commands entered by the user, CP messages space is again available, the operator can and responses, and messages from or to the restore the dumped spool files to the system operator. Console spooling is system for subsequent processing. !he invoked by the SPOOL CONSOLE command. It files spooled to tape can also be hand is particularly useful when the virtual carried and loaded into another VM/SP console is a display device or when the system for output spool file processing. virtual machine is executing with the terminal disconnected, because the virtual Specific files can be transferred from console output, which would otherwise be the spooled card punch or printer of a lost, is saved on disk. The saved data is virtual machine to the card reader of the later printed on the real printer. When a same or another virtual machine. (A console spool file is closed, it becomes a virtual card reader is not limited to printer spool file. SO-character records.) Files transferred between virtual unit record devices by the In diagnostic applications, spool spooling routines are not physically console output is beneficial in the punched or printed. The CP spooling reconstruction of events that preceded a support can make files available to real or virtual system abend. multiple Rirtual machines, or to different operating systems executing at different times in the same virtual machine. Remote Spooling CP can print multiple copies of a single spool file, backspace any number cf printer pages (or backspace the complete file), and CP, in conjunction with remote spooling define spooling classes and output form for facilities, can transmit files across a real output files. teleprocessing network. The "Remote Spooling Communications" section ~ater on CP commands transfer and sequence in this book describes how this is done and (order) spool files. CP commands use how it is used.

22 IBM VM/SP Introduction CP Commands computing system. However, the C~S user can issue CP commands without leaving the CMS environment, that is, without signaling CP commands are used interactively by an attention interrupt. operators and systems personnel to control the real computing system and V~/SP, and by users to control virtual machines and their operating systems. Privilege Classes Normally, CP commands can be used at any time, withcut regard to which operating Each user of VM/SP is assigned one or more system is controlling the user's virtual privilege classes as part of the directory machine. To issue CP commands, the user entry of his virtual machine. The must first suspend execution in the virtual privilege classes define the subset of CP machine by signaling an attention interrupt commands that each user can execute. See to VM/SP's control program; a virtual Figure 7 for a concise description of each machine attention interrupt is eguivalent privilege class. to pressing the stop button on a real

r I Class User Function I ------1 Al Primary System Operator !o be responsible for the avail- I Note: The class A user ability of the VM/SP system, its 1 who is logged on at CP communication lines, and resources.J initialization is In addition, the class A user J designated as the controls system accounting, broad- I primary system operator. cast messages, virtual machine per­ formance options and all other commands that affect the overall performance of VM/SP.

Bl System Resource Operator ~o control all the VM/SP real resources, except those controlled by the class A or class D user.

Cl System Programmer !o update certain functions not controlled by other privileged class users.

Dl Spooling Operator To control all spooling data and specific functions of the unit record devices. 1--- I El System Analyst To examine and save specific data J in the VM/SP storage area. 1------I Fl Service Representative To obtain and examine, in detail, 1 certain data concerning the I/O I devices connected to the VM/SP I system. General User Control functions associated with the execution of the users virtual machine.

Any User commonly used commands that are available to all users of VM/SP for a variety of uses.

H Reserved Beserved for IBM use only.

IDescribed in the !M/SP Q~~toL§ QYid~ 2Described in the VM/SP CP £2!!U!!ill Re!~~~ fo!:: ~!!~,g! ~ igure 7. CP Privilege Class Descriptions

Control Program 23 GENERAL USERS This flexibility of system operation, along with CP's VARY ON/OFF PROCESSOR command, facilitates system reliability, A general user can issue commands that availability and serviceability (RAS). RAS control functions associated with the is enhanced because main components of a execution of his virtual machine. system complex can be placed offline for system repair or upgrade at a time that A complete list of the general user minimally impacts system operations. commands and their descriptions, are Later, when the full resources of the located in the VM/SP CP comma~g Refer§~£~ system are needed and available, the 121: Ge~! Users. processor can be varied online and attached processor mode reestablished.

OTHER USERS MULTIPROCESSOB SUPPORT Users, other than the general user, can perform additional functions by issuing VM/SP multiprocessor support functions in a commands to dynamically provide VM/SP manner that is similar to attached performance options, to terminate a processor support except that I/O can particular virtual machine and many other execute on both processors simultaneously. similar functions. Because VM/SP can be initialized by either processor, I/O paths should be provided to the system residence device and critical CP-owned DASD from both systems in case one VM/SP Attached Processor and system's channels or processor has to abort operations. Establishing parallel paths to Multiprocessor Support critical I/O devices allows automatic system recovery on the rema~n~ng system configuration. Depending on the magnitude ATTACHED PROCESSOR SUPPORT of the malfunction, recovery can result in the system's continuing operations in multiprocessor mode with one or more On systems that are either an attached channels marked offline. processor complex or an asymmetric multiprocessor complex, VM/SP has a mode of "'''------,,------.. operation that takes advantage of the additional computing power that such Virtual Machine Communication Facility systems provide. This mode of operation is called attached processor mode. In this mode two instruction processors The Virtual Machine ommunication Facility simultaneously execute multiple tasks from (VMCF) allows one virtual machine to a common queue while sharing the same main communicate and exchange data with any storage. othei virtual machine operating under the same VM/SP system. With attached processor mode, the main processor controls and performs all I/O This is accomplished via a DIAGNOSE activity. In the event of a severe instruction utilizing a special parameter nonrecoverable malfunction in the attached list. VMCF locks one data .page for the processor hardware, VM/SP may continue sender and one for the receiver during the operations with the main processor transfer. As a result, data transfer is executing in uniprocessor (or one faster because VMCF moves information processor) mode. (Note, the main processor directly from the sender's virtual storage is the processor equipped with channel and to the receiver's virtual storage. The I/O devices.) If the system complex transfer does not involve devices because supports Channel-set switching, and a VMCF uses userids to logically address data severe nonrecoverable hardware error is from one virtual machine to other virtual associated with the main processor, the machines. system may still be able to perform in uniprocessor mode. It does this by A virtual machine can have one to 50 dynamically switching the channel set (all active communications going on with other active channels of the main processor) to virtual machines. The amount of data that the other processor, thereby, utilizing the can be transferred in a single operation is attached processor as the main processor. limited only by the virtual storage size of the virtual machines involved in the transaction.

2q IBM VM/SP Introduction A more detailed descripticn of VMCF under control of a changable message functions and how they can be invoked in a routing table. virtual machine is contained in the VML§~ system programmer's 2uid~. Programmable operator can be used by a stand-alone VM/SP system or be controlled by an operator at a host VM/SP system. Remote operation of a VM/SP system reguires Communication Vehicle Release 2 or 3 of the ~S Netw~ing ~ program product on both of the V!~ systems. Release 3 of the RSCS Networking The Inter-User Communication Vehicle (IUCV) program product provides improved display defines a precise communication protoccl usage. for dialogue between virtual machines operating under the same VM/SP system. IUCV communications are accomplished by TRACE TABLE RECORDING FACILITY the use of a special privileged instruction operation code. Up to 32,767 bytes of information can be transferred in a single The Trace Table Recording Facility IUCV operation. The information is moved preserves selected trace table records plus from the sender's virtual storage to the CP and virtual machine interface records by receiver's virtual storage. recording them on a CP spool file. The facility, invoked by the command CPTBAP, is other features include: intended for the analysis of VH/SP problems that escape detection using a system dump. • User directory entries to control IUCV authorization and use The CPTRAP command creates a READER spool file. A CMS data reduction program, • nUltiple communication paths between TBAPRED, is provided to allow use of the virtual machines data collected. Using the spool file as input, output can be either a spooled print • User control to selectively enable and file or an interactive terminal display. disable IUCV interrupts for priority and This allows: nonpriority messages, for priority and nonpriority replies, and for IUCV I. selectivity of output control interrupts I. positioning within the file I. displaying data in a forward or backward • User ability to receive messages and I direction replies either synchronously or I. printing asynchronously (via external interrupts) I. stopping • Tracking IUCV function in the CP trace CP servicability is enhanced in that table CPTRAP support allows Field Engineering to collect problem determination information • Communicating with Console Communication via a telephone conversation with site Services (CCS), a function of VM/SP's personnel, who can be told how to set up a control program, by authorized virtual CPTRAP run before recreating the problem. machines For detailed information concerning the For details on the functions performed by use of the Trace Table Recording Facility, IUCV, refer to the !l1L.§~ ~§1~ refer to the !M/S~ Sys~ programmer's ~~a!!!~C§ Guide. Gui,g~.

! PROGRAMMABLE OPERATOR SUPPORT

The Programmable operator facility can be used in a VM/SP system to reduce or eliminate system operator message activity. It provides a capability to:

• log messages • suppress messages • redirect messages • execute commands • preprogram message responses

Control Program 25 26 IBft Vft/SP Introduction Conversational Monitor System

The conversational monitor system (CMS) is The read-only system disk contains the a major component of VM/SP. Together with CMS nucleus, disk-resident CMS commands, the control program of VM/SP, it Frovides a and the system library. The CMS system time-sharing system suitable for direct disk can be shared among CMS users. prob1em solving and program development. CMS is an operating system that executes in The read/write disk contains the user's a V~/SP virtual machine. (CMS uses the permanent and temporary files. CMS disks Diagnose interface for all of its disk and must be assigned in units of full cylinders tape input/output operations and relies on for CKD DASD or blocks for FEA devices. CP's error recovery routines.) Figure 8 shows a virtual machine The user can create, update, and configured to execute CMS. A minimum eMS manipulate files as well as compile, test, configuration would not include the virtual and execute problem programs. These tapes. interactive capabilities are extended to DOS users via the CMS/DOS environment of CMS. For OS/VS users, a comtination of CMS commands and CMS ·simulation of OS macros CMS provides similar interactive capabilities.

CMS supports the same DASD that are supported by CP (with the exception of the CMS Configuration 2305). CMS formats the tracks of a CMS disk into fixed-length blocks. !he eMS file system then manages these blocks in A virtual machine that is to use CMS is such a way that the user appears to have configured much the same way as any other logical fixed- or variable-length records, virtual machine, with a few special and sequential or direct access to files. considerations. In addition to reading and writing CMS The CMS virtual machine must be assigned files, CMS can read, but not write, DOS at least 256K bytes of virtual storage. sequential, CS sequential, and OS User programs that execute in CMS may partitioned datasets. CMS can read and increase this requirement. !he virtual write VSAM datasets. storage size may be defined as large as 16 megabytes, in multiples of 4K. Problem programs that execute in eMS can create files on tapes in any record and Additional portions of CMS can te shared block size; the record format can be fixed, in discontiguous segments. Discontiguous variable, or undefined. segments can be automatically attached to and detached from the CMS virtual machine Except for the EXEelO command, CMS as needed. A name is aSSOCiated with one automatically opens and closes all accessed or more discontiguous segments. Some, all, files (including spool files) for each or none of the discontiguous segments can command or user program it executes. Files be shared. Discontiguous segments must be can be spooled between virtual machines to loaded at addresses beyond the highest transfer files between users. Service address in the virtual machine. programs invoked by CMS commands also manipulate files. CMS files can be written CMS supports unit record devices only if onto and restored from labeled and they are virtual and use the CP spooling unlabeled tapes via CMS commands. For more facilities. Real unit record devices details on this, see the heading: "CMS Tape cannot be dedicated to the CMS machine Label Processing." because CMS has no unit record error recovery procedures. CMS has files that contain macro libraries and program libraries, and CMS supports tape and disk devices, but commands to use and update these litraries. disk volumes are the primary external The user or installation can create storage for CMS command processing. additional macro and program libraries, if needed. Generally, each CMS user is assigned at least two disks: a read-only system disk and a read/write user disk.

Conversational Monitor System 27 Virtual Storage

Virtual Card Reader/Punch

Figure 8. Sample CMS Configuration

USER DISKS • filename (fn) -- is an a-character name assigned the file by the user.

CMS requires the system residence volume to • file type (ft) -- is the identification be online. In addition to the system disk, g1ven to specify particular file each user may have up to 25 virtual disks characteristics. online at anyone time. (All 25 of these disks can reside on one real disk.) • filemode (fm) identifies the disk that contains the file and the access The user disks are differentiated by a mode assigned to the file. filemode letter designation, assigned when the disk is made active. The file mode letter (A-Z) defines a standard order-of-search for disk tiles. The SAMPLE ASSEMBLE An standard order-of-search is seguential from A through Z. The search order can be modified by a CMS command. ~he user's Figure 9. CMS Pile Identification knowledge of the arrangement of files on CMS disks coupled with a search order modification can significantly reduce the Pigure 9 is a sample C~S file identifier time required to locate the desired files. with an identification of SAMPLE, ASSEMBLE If duplicate file identifiers exist for indicates that the file consists of different files on different disks, and the assembler language source statements, A files that are to be retrieved are located indicates that the file is located on the on a disk further on in the search order, A-disk directory, and n is the filemode then altering the search order is the number (the default value is 1). procedure for retrieval. One method of file creation is a result Each virtual disk may be defined as of using CMS commands, for example: XEDIT read-only or read/write, and may be shared or COPYPILE and specifying the filename, among users. filetype, filemode of the file being generated. Other CMS files are created and given file default identifications by the CMS command process itself. PILE IDENTIPICATION

CMS user files are identified by a fileid consisting of three designators:

28 IB~ VM/SP Introduction PILE STRUCTURE CMS Command Language

CMS disk files are written as fixed-length ~he CMS command language is flexible and records, which usually are not physically can be tailored by the installation or by contiguous on the disk. They are allocated individual users. and deallocated automatically by CMS as the file size demands. The user can elect Most CMS commands can be entered by the 102Q, 204B, or Q096 byte record blocks as a user in a truncated form (for example, "a" substitute for an BOO byte block can represent "assemble"). CMS keeps an allocation. Each virtual disk has a master ordered list of command names, from which file directory, or the subset called user it determines which command the truncated file directory, containing format and size form represents. The installation can information for each file on the virtual modify the sequence of the command list and disk. This directory includes a pCinter to the valid limits of truncation. a chain of records that are the actual files. Each user (or installation) can defi~~ synonyms for any or all command names. ~ For SOO-byte record disks, a single user file is limited to a maximum of 65,533 Any executable program stored on a CMS records and must reside on one virtual system or user volume can be invoked by disk. The file management system limits name as a command. To execute a program, the number of files on anyone virtual disk the user must enter on the terminal the to 3400 (3500 files on a 2314). CMS disk program name, followed by any required files that are written as BOO-byte records operands. are chained together by a specific file entry that is stored in a tatle called the In addition to the above, CMS provides master file directory; a separate master as an aid to all users, a command file directory is kept for, and on each facility. This facility allOWs users to virtual disk. The 3310 and 3370 disk display pertinent information on all CMS' storage devices are not supported by the commands, all CP General User Commands, and old (BOO-byte) CMS file system. system messages. The CMS HELP facility has function that permits users to tailor this For 1024-byte, 204B-byte, or 4096-tyte text data base by the addition and record disks, a single user file is limited subtraction of information to fit the to a maximum of 2 31 -1 items and must reside installation's user population needs. The on one virtual disk. The file management user can modify this data base to include system limits the number of files on any commands and programs of his own creation. one virtual disk to 231-1. The EXEC processors of CMS, that is CMS ~ and EXEC 2, can be used to define new commands that are combinations of existing Initialization and Dump Restore commands. Such new commands, called EXEC procedures, eliminate the tedious rekeying of frequently used sequences of commands. The Device Support Facilities Program The EXEC prOcessors have logical (5747-DS1) standalone version is used in a capabilities; EXEC procedures can test the virtual machine or in a standalone manner contents of variables, branch on specified to initialize Count Key Data (CKD) or Fixed conditions, and execute programmed loops. Block Architecture (FBA) formatted tASt or A special EXEC procedure, named: PBOFILE minidisks for OS or DOS. Alternatively, a EXEC can be invoked automatically when the guest SCP may be used to initialize CKD user issues his first command in the CMS DASD. environment; information in the PROFILE EXEC can contain CP and CMS commands that The CMS FORHAT command initializes upon automatic execution tailor the virtual minidisks for CMS. machine to meet the user's immediate terminal session requirements. A CP format program formats CP-owned volumes, such as the system residence, The EXEC 2 processor handles EXEC 2 paging, and spooling disks. programs. EXEC 2 programs and EXEC 2 processing are similar to CMS EXEC programs The DASD Dump Restore (DDR) program of and CMS EXEC processing. The EXEC 2 VH/SP, which executes standalone or under processor provides advanced EXEC CMS, dumps, restores, and displays all programming capabilities and improved types of real disks and minidisks. performance for the CMS user.

You may not use CMS EXEC language statements in a program to be interpreted

Conversational Monitor System 29 by the EXEC 2 processor, nor EXEC 2 which is placed in front of the PL/I source language statements in a program to be program. interpreted by the CMS EXEC processor. However, you may call an EXEC 2 program The ,DOS linkage editor is simulated in from a CMS EXEC program, and vice versa. CMS. Files to be-link-edited can be read from DOS litraries. CMS link-edits files Since both CMS EXEC and EXEC 2 files are and places the output 'in a cMs fl.le (witn-a­ called in the same way, CMS examines the file type of DOSLIB) and accepts most of first statement of the EXEC file to the DOS linkage editor control statements determine which EXEC processor must handle as input. it. If the first statement of the EXEC is &TRACE, CMS calls the EXEC 2 processor to handle it. I~ the first statement is not &TRACE, CMS calls the EXEC processor to LANGUAGE PROCESSORS handle it.

See the publication l~L~g ]XEC ~ A VM/310 assembler is distributed as part ~ef~~ for further information about of the VM/SP system and is required for EXEC 2. See the publication ]~~g C~§ installation and support. All necessary User's ~ for further information about macros for installation and support are CMS EXEC. provided in CMS libraries.

A variety of programming languages are available for use with CMS. VS APL, Program Development and Execution V5BASIC, DOS and OS PL/I, OS , and VS FORTRAN are useful languages for problem-solving applications. DOS/VS, CMS has a wide range of programming OS/VS COBOL, DOS and OS PL/I, DOS/VS RPG development capabilities, it can: II, and assembler language programs assembled with the VM/SP assembler are • Create and compile source programs useful for commercial program development • Build test files applications. • Execute and test programs • programs at the terminal Most object programs produced and compiled under CMS may be executed under CMS for direct problem solving. Programs that use certain OS or DOS system functions PROGRAM COMPILATION AND EXECUTICN COMMANDS must be run under the appropriate operating system.

When a compiler is invoked, CMS dynamically allocates compiler work files on whichever active user disk has the most available INTEGRA~ED EMULATORS space (the location of these work files may also be specified by the user), and deallocates them at completion. Compiler Emulator-dependent programs (except for DOS object decks and listing files are normally emulation under OS or OS/VS) that execute allocated on the same disk as the input on a System/310 equipped with the source file or on the primary read/write appropriate compatibility features can disk (normally, the A1 disk). ~hey are execute on that System/310 in VSE or OS identified by the input filename together virtual machines under VM/SP. with the filetype TEXT or LISTING. No modifications are required to be made The compilers executable under CMS are to emulators, to DOS or OS, or to VM/SP to invoked by name and provided with a source allow emulator-dependent programs to file whose filetype designator indicates execute in virtual machines. the compiler. On each of the command lines, the user can specify CMS options, In an attached processor (AP) or and also language processor options, that multiprocessor (MP) system, a virtual are identical to those coded on an OS EXEC machine can use the SET AFFINITY command to card when the language processor is invoked make use of an emulator installed on only from Os. The DOS/VS COBOL user specifies one of the processors. The directory the compiler options on an OPTION command option for affinity may be used instead, which precedes the FCOBOL command. with similar results. Compiler options can also be specified using the CBL control statement in the COBOL program. The PL/I user must specify compiler options on an *PROCESS statement

30 IBM VM/SP Introduction THE CMS EDITORS error messages to be printed at the terminal, and whether unknown commands should be passed on to CP. With the QUERY CMS contains two editors; one is referred command, the user is given the current to as the CMS Editor, the other, the status of these and other CMS functions. VM/System Product Editor. Synonyms for command names may be The CMS Editor consists of the EDI~ created by a user via entries in a CMS file command and its subcommands. With the CMS with a tiletype of SYNONYM. Editor, a user can create a file by·typing the data in at the terminal. He can scan The EXEC command specifies a file of CP all er part of the file, and insert, and C~S commands, as well as conditional change, or delete records. The CMS Editor branching and control statements, which are is a line editor; that is, the target fer executed in a predetermined sequence ty one editing is one line of text at a time. of the EXEC precessors of CMS.

The system Product Editor consists of the XEDIT command and its sutcommands and macros. It is both a full screen and a CMS TAPE LABEL PROCESSING line (or typewriter) editor. ~he VM/SP editor provides expanded function that will allow, in addition to mest of the Tape label processing exists only in CMS capabilities of the CMS editor: and is not used by the CP function that provides tape output. CMS tape label • Multiple views of the same file er processing includes the following: different files on the display screen • Routines to check IBM standard labels on • The issuance of selected commands from inFut the displayed line • Routines to write IBM standard labels on • Provides language expansion through the output

~ • The facility to specify user exits for • Plus ether function processing nonstandard labeled tapes during execution of CMS macro Both editors, however, remain available simulations and some CMS tape operation in order to facilitate migration. See the commands publications Y]L~g Syste~ ~~oduc! Edi!~~ Use~~ Guide and the VMLSP .§.1.§tem irod,Y.£! • The facility to specify user-written Editor Command and Macro Reference for routines to process standard user labels further information -about --the---System during DOS and OS macro simulation under Product Editor. Details on the CMS editor CMS is contained in the 1M/SP £~.§ Us~~§ Qy~g~ and in the VMLS~ £MS CO.l!!!!ang ~nd 1!~ • A modified CMS tape command that Refer~.!!.£~. displays the VOLl label on read commands and writes a new VOLl label on write operations

SCRIPT/VS • A facility to bypass label processing or to process tapes without labels SCRIPT/VS is a text processor available as eMS supports the processing of IBM a program product for use under C~S. standard tape labels for OS simulation, SCRIPT/VS includes manuscript facilities CMS/DeS, CMS commands and the TAPESL macro. that create formatted output .from one or It also supports user written nonstandard more CMS files containing text and/or tape label processing routines fer OS text-manipulating control words. simulation and CMS/DOS.

CONTROL COMMANDS ALTERNATING OPERATING SYSTEMS

The CMS user is able to define certain If a program to be tested uses OS and DOS system functions with the SE~ command. ~he functions that are not simulated, or if the functions include: the amount of program is designed for some other information in the message printed at the operating system, the user may execute the end of command proceSSing, the type of two operating systems alternately. The

Conversational Monitor System 31 virtual machine must be configured to run user to set instruction address stops in both CMS and the other operating system. his program, to examine and modify virtual registers and virtual storage, and to trace Using this technique, the user first all SVC interrupts. User-selected loads the Conversational Mcnitor system interrupts may be traced with output into the virtual machine. An editor is directed to either a virtual printer or the used to make any necessary updates to the terminal. source program. Spooling facilities are used to copy the program (integrated into a suitable operating system job stream) into the virtual card reader. The user then CMS BATCH FACILITY issues the IPL command to load his other operating system and begin the comFilation. When the job stream completes, the . user The C!S batch facility is a VM/SP must reload CMS with the IPL command. ~he programming facility that executes under spooled printer output generated by the CMS. It allows a VM/SP user to execute other operating system can be read onto a jobs in batch mode by sending jobs from CMS u~er disk, inspected for diagnostic either his own virtual machine or the real messages, then optionally scheduled tor card reader to a virtual machine dedicated printing. Corrections and additional to running batch jobs under the batch compilations, if necessary, tollow the same tacility. The batch facility virtual procedure. machine then executes these jobs, freeing the user's virtual machine for other uses. The accounting routines charge the time used in the batch machine to the DEBUGGING FACILITIES originating user. For details on using CMS Batch, refer to The debugging facilities of CMS Fermit a the V!L~g CM~ Y~f~2 Guig~.

32 IBM VM/SP Introduction Remote Spooling Communications

Telecommunication support to transfer files • Remote stations to job entry batch between remote stations and virtual systems machines using binary synchronous (ESC) switched or nonswitched lines can be • Remote stations to a CMS batch virtual accomplished by either of the fcllowing machine programs: Some examples of remote job entry batch • Remote Spooling Communications sutsystem systems are: HASP, ASP, JES, RES, (RSCS), a component of VM/370 Release 6 VSE/PCiER, and CRJE. These job entry batch systems, run under the aFproFriate system • Remote Spooling Communications subsystem contrel program such as: DOS, DOS/VSE, OS, (RSCS) Networking program Product or OS/VS. (57'18-XP1) Both of these programs have a supervisor Both programs contain similar function; and line drivers. The supervisor is an however, the RSCS component of VM/370 has interface between the CP spool system and not been updated for Vft/SP. It does not the program's line driver. The line utili2e any of the VM/SP enhancements that drivers drive, or control, a specific type have been added since VM/370 Release 6. of remote station. The RSCS component of VM/SP cannot: Figure 10 shows the relationship among the virtual machine users, the CP spool handle virtual 3800 files system, and the remote stations. use a system disk formatted in 1K, 2K or Remote station eguipment consists of 'IK block si2e supported card and printer devices as well as processor configurations. Remote ,- use a system disk on a 3375, 3380 or FEA stations as defined for use with either device RSCS or RSCS-Networking includes both programmable and nonprogrammable types. use a dedicated remote 3270 information display printer Programmable remote stations are I/O configurations that include a computer, RSCS-Networking is the recommended such as a System/3, System/32, System/360, product to use with VM/SP. or System/370. If this computer is running a HASP-type or ASP-type batch processor, Either of these programs using the spool the remote station can receive files file system of CP, provides a transmitted across the RSCS network, telecommunication environment for the process the files, and transmit the results transfer of files from: of the processing back to the originating location. Otherwise, the programmable • Virtual machines to remote stations remote station can only receive, read, print, punch, and send files. In other • Remote stations to other remote stations words, if the programmable remote station does not have a HASP- or ASP-type of batch • Virtual machines to remote job entry processor, it acts as though it were batch system nonprcgrammable.

Remote Spooling Communications 33 VM/SP REMOTE STATIONS

Nonprogrammable Remote Station VM/SP Virtual Machines

OSIVS1 CONTROL PROGRAM

Virtual Machine CP Controlling Spool ..---+-- ..... ~ Remote System Programmable OS/360 Spool Remote Station HASP Batch Operations Processor

CMS Programmable Remote Station

Figure 10. Relationship Among Virtual ~achines, Remote Stations and CP's Spool System

Nonprogrammable remote stations are I/O Por information concerning RSCS configurations that cannot be programmed, Networking, refer to the RSCS Networkinq but can receive, read, print, punch, and General Information Manual, GH24-5004 and send files. An example of a the BSCS- NetworkIiiq PrOgram Reference and nonprogrammable remote station is a 2780 Ope~ati~§ ~~~1, SH24-5005. Data Transmission Terminal. Por information on the RSCS component of VM/370, Release 6, refer to the ~SCS User's Qyig~, GC20-1816.

3q IBft Vft/SP Introduction Interactive Problem Control Systems

The Interactive Problem Control system Function is included with IPCS Extension (IPCS) Extension Program Product (5748-SA1) prog~am product to be compatible with can be used to standardize the V~/SP multip~ocessor support provided in VM/SP. problem reporting process. This Froducticn Therefo~e, the IPCS prog~am product is the enhances the serviceability of VM/SP by suggested problem report generation program identifying recurring programming problems to be used with VM/SP. located on the user base. Additional environmental conditions can also be For more information on this Froduct, included in problem reports: usez detected ~efer to the !PC~ ExteB§!QB Program groduct problems can be entered, uFdated, and Gene~al Infonation Manual, GC3Q-2019 and printed out; and the problem data base can the il£.a Extension User'§ Guide and be interrogated for individual Fzoblems. Reference, SC34-2020. The function of generating protlem ~eports is accomFl~shed by IPCS Extension commands. Similar problem reporting is provided by These commands are used to gene~atE a the IPCS component of VM/370 Release 6. disk-resident report. This report, along However, this component is not recommended with the early warning system (EWS) for use with VM/SP as it has not been microfiche, gives speedier identificat~cn upgraded to perform with the unigue of previously reported problems. functions of VM/SP, nor does the IPCS component contain all the function provided The use of IPCS Extension: by the IPCS Extension program product. • Facilitates online problem management The following is the list of what the and interactive problem diagnosis. IPCS component of VM/370 should not be used for in a VM/SP environment: • Provides an analysis function for CP dumps; the resultant extracted data 1. Analysis, formatting, and printing of resides on disk as a unigue Frotlem CP dumps taken when running in MP report. mode. • Has a prompting prcgram for 2. Analysis of CP dumps with an abend user-detected failures; the ~esultant code added since VM/370 Release 6. data resides on disk as a unigue protlem report. In addition, the user should be aware that control blocks will be formatted in • Searches for duplicate Frotlems and Release 6 format (except for the RECBLOK info~ms the user when a problem with which will not be formatted at all). If a similar symptoms was p~eviously block bas been extended since Release 6, experienced at the installation. the extension will not be formatted. • Has a problem-tracking facility that For information regarding the IPCS updates and displays problem status. component of VM/370, Release 6, refer to VM/370 ~active Prob!!!! Control System • Has an interactive debugging facility IIPCS) User!2 Guide. For information on that aids in the analysis of the installation of the IPCS component of disk-resident CP abend dumps. VM/370, see the !~.ag Planning sag lIst~! Qga~s!i2B, 5C19-6201.

Interactive Problem Control Systems 35 36 IBft Vft/SP Introduction Appendix A: VM/SP Audience-to-Publication Relationship

The following illustrates the relationEhip Audiences of VM/SP may extend beyond the of the VM/SP audience to appropriate categories listed in the following chart. publications. Also included is a brief Such users should consult the VM/SP description of the text content. GIQ2§s~l 2n~ ~2§!££ !B££Z, GC19-6207, to locate the topics and the related books that suit their needs. r------Audience IputlicationE IContent

All users IVM/SF Introduction, IOverview of VM/SF and IGC19-6200 Ivirtual machines I IVM/SP CP Command IG and "Any" commands IReference for General Ineeded for virtual IUserE, SC19-6211 Imachine control I I IVM/SF SYEtem Messages IAbend codes, wait land CcdeE, SCl9-6204 Istates, and messages I IVM/SF ~erminal User's 11ogOD/logoff, virtual, IGuide, GC19-6206 Iconsole terminal use, I lattention handling I IVM/SP Quick Guide for IReference for command and IUsers, S120-4400 Iservice program control I Istatement formats I ICMS Frimer, SC24-5236 IIntroductory description I lof VM/SP CMS. system Analyst, IVM/SF General ISynoFsis of VM/SP, brief Programming system IInformation Manual, Idescriptions of unique Representatives, IGC20-183S IVM/SP function, planning Installation Plannersl linstallation and and Support Personnel I I distribution information. I IVM/SP Planning and IVM/SF installation ISYEtem Generation I~equi~ements and IGuide, SC19-6201 I procedures I IVM/SF operator's Guide,IVM/SF system control ISC19-6202 Icommands, resources, I Icontrol, service I Iprograms, spooling I IVM/SF system IResources fer problem IProgrammer's Guide, Isolving, tracking, ISC19-6203 Itracing, monitoring I IVM/SF operating SystemslRelationship of VM/SF lin a Virtual Machine, Iwith ether operating IGC19-6212 Isystems, VM/SP concepts I IVM/SF OL~SEP and Error ICLTS from a virtual IRecording Guide, I environment. RMS, ISC19-6205 linvoking CPEREP

Appendix A: VM/SP Audience-To-publication Relationship 37 i I I I I Audience Iputlications I Content 1------ISystem Analyst, IVM/SP CMS Command and ICMS facilities for IProgramming System IMacro Reference, Igenerating, compiling I Representatives, ISC19-6209 lediting, testing and IInstallation planners ------Idebugging programs and Support Personnel VM/SF CMS User's Guide,1 (cont.) SC19-6210 I

OS/lS, DOS/1SE, VM/370 I Provides details on Environmental RecordingIOS/VS, DOS/VSE, VM/370 Editing and Printing, land VM/SP EBEP operands GC28-0772 linvoked by CPEREP

VM/370 Interactive ICatalog and update Protlem Control system Ifacilitj for recorded (IPCS) User's Guide, Isystem and virtual GC20-1823 Imachine problems

I.VM/SP Service Routines VM/SP logic on CP, CMS, IProgram logic, IPCS and RSCS; the I LY20-0890 service programs; EREP I and the data areas and IVM/SP Data Areas and control blocks that IControl Block Logic, relate to those I LY20-0891 components 1------IVM/SF system Logic and IProtlem Determination, IVol 1 - CP, 1120-0892 IVol 2 - CMS, L120-0893 I IVM/370 System logic and IProtlem Determination, IVol 3 - ESCS, S120-0888

1------10S/lS, DOS/VSE, VM/370 IEnvironmental Recording IEditing and Printing I (EEEP) Program Logic, ISY28-0773

IField Engineer (CE) IVM/SF OLT~EP and Error IOLTS from the virtual I IRecording Guide, Imachine, RMS, and I ISC19-6205 IInvoking CPEREP I 1------I 10S/VS, DOS/1SE, VM/370 I Erovides details on OS/VS I IEnvironmental RecordingIDOS/VSE, VM/370 and VM/SP I IEditing and Printing IEREP operands invoked by I IGC28-0772 ICPEREP 1------ISystem operator IVM/SF operator's Guide,IResource and system I SC19-6202 Icontrol command and Iservice programs; VM/SP linitialization and I shutdown

lM/370 Remote Spooling ICperational control of Communications Iremote spooling sutsystem (RSCS) User'sl Guide, GC20-1816 I

VM/SP CP Command IG and Any commands -­ Reference for General Irequired for virtual Users, SC19-6211 Imachine control

38 IBM VM/SP Introduction I I Audience Ipu1:lications I Con tent system operator IVM/SF Operating SystemslBelationshi~ of VM/SF (cont.) lin a Virtual Machine, Iwith ether operating IGC19-6212 I systems 1 IVM/370 Interactive ITracking facility for IPrcblem Control System Isystem and virtual I (IPCS) User's Guide, Imachine problems IGC20-1823 I 1------IVM/SP OLiSEP and Error IHow to invoke CPEBEP to IRecording Guide, Icapture/clear SYS1.LOGREC ISC19-6205 land VM/SP error cylinders I I Application VM/SF CMS Command and ICMS command formats for IProgrammer, HacJ:o Reference, I program creation, edi~ing IInteractive users -­ SC19~6209 Itesting and debugging IAnyone who needs to create or modify VM/SP CMS User's GUide,IDetailed use of CMS programs or data SC19-6210 ICMS commands VM/SP EXEC 2 Beference,IDetailed use of the SC2Q-5219 IEXEC 2 proce~sor VM/SF System Product lTutorial information for Editor User's Guide, I using the System Product SC2Q-5220 I Editor VM/SP system product IDetailed use of the Editor Command and ISystem Product Editor Macro Reference, I Commands GC2Q-5221 I

Ap~endix A: VM/SP Audience-To-Publication Relationship 39

Appendix B: Related Publications for eMS Users and Other Applications

This appendix attempts to alert users of VS BASIC: Quick Guide for CMS SX28-6386 some of the publications that sUPFort Users program products that run in CMS or other VS BASIC: Installation Reference SC28-8309 virtual machines. These program products Material provide supportive services fcr CF or CMS. VS BASIC: Language Reference GC28-8303 Keep in mind that this list contains only a Manual few of the supportive products and a still smaller list of related publicaticns.

Since titles change and new publications are constantly being added to the IBM MATH/BASIC, General Information GH20-1128 library, this list only serves as a guide Manual to what is currently available. Another MATH/BASIC, Program Reference SH20-1158 source for documents that relate tc program Manual products is the IBM sys1~!L370 g~g ~300 SiAT/BASIC, Program Reference SH20-1069 Pro~~ Bibliog~, Order No. Manual GC20-0001. STAT/BASIC, General Information GH20-1027 Manual As CMS is a basic requirement for the Business Analysis/BASIC, Program SH20-1264 use of many of the other program products, Reference Manual its document requirements (including Business Analysis/BASIC, General GH20-1175 corequisite publications) are listed first. Information Manual

VM/SP Quick Guide for Users SX20-4400 C~S for , A Primer SB20-4438 CMS Primer SC24-5236 VM/SP CMS Command and Macro SC 19- 6209 OS/VS and VM/370 Assembler GC33-4021 Reference Prcgrammer's Guide VM/SP CMS User's Guide SC 19- 621 0 OS/VS, DOS/VS, and VM/310 GC33-4010 VM/SP EXEC 2 Reference 5(24-5219 Assembler Language VM/SP System Product Editor SC24-5220 VM/SP: System programmer's . SC19-6203 User's Guide Guide VM/SP System Product Editor SC24-5221 Command and Macro Reference

Document Composition Facility: SH20-9160 Coregyisitg publications Generalized User's Guide Document Composition Facility: SH20-9161 VM/SP Introduction GC 19- 6200 User's Guide VM/SP System Messages SC19-6204 VM/SP Terminal User's Guide GC19-6206 FOR1RAN Note: In some cases, the titles are abbreviated to save space. VM/370 (CMS) Terminal User's SC28-6891 Guide for FORTRAN IV Program. Products IBM FORiRAN Program Products for GC28-6884 OS and the CMS component of VS BASIC CMS Terminal User's 5(28-8306 VM/370: General Information Guide IBM OS Code and Go FORTRAN and SC28-6853 B is for BASIC. An Introduction SC28-8310 FORTRAN IV (G1) programmer's to VS EASIC under CMS Guide VS BASIC, General Information GC28-8302 FORTRAN IV (G1) Processor and SC28-6856 TSC FORTRAN prompter for OS and VM/370 (CMS): Installation Reference Material

Appendix B: Related Publications for CMS Users and Other Applications 41 IBM OS FORTRAN IV Library SC28-6858 Guide (Mod 1) for OS and VM/370 as COBOL Interactive Debug SC28-6465 (CMS) Installation Reference Terminal User's Guide and Manual Reference IBM Code and Go FORTRAN SC28-6859 as COBOL Interactive Debug SC28-6468 Processor for OS and VM/370 Installation Reference (CMS) Installation Reference Material Material OS/VS CCBOL Compiler and Library GC28-6470 IBM OS FORTRAN IV (H Extended) SC28-6852 General Information compiler, Programmer's Guide OS/VS COBOL Compiler and Library SC28-6481 IBM OS FORTRAN IV (H Extended) GC28-6865 Library Installation Reference Compiler and Library (Mod II), Material Messages OS/VS COBOL Compiler and Library SC28-6483 IBM FORTRAN IV (H Extended) SC28-6861 programmer's Guide compiler and FORTRAN Library DOS/VS COBOL Compiler and SC26-6478 (Mod II) for OS and VM/370 Libra~y Programmer's Guide (CMS) Installation Reference DOS/VS COBOL Compiler and SC28-6479 Material 'Lib~ary Installation Reference IBM OS FORTRAN IV Mathematical SC28-6864 Material and Service Subprograms VE/370 CMS Use~'s Guide SC28-6469 Supplement for Mod I and for COBOL Mod II Libraries IBM VS COBOL for DOS/VSE GC26-3998 IBM FORTRAN IV Library GC28-6818 Mathematical and Service Subprograms FORTRAN Interactive Debug for OS SC28-6886 VSE/Advanced Functions Macro SC24-5210 (TSO) and VM/370-CMS User's Guide Installation Reference Manual VSE/Advanced Functions Macro SC24-5211 FORTRAN Interactive Debug for OS 5C28- 6885 Reference (TSO) and VM/370 (CMS) VSE/System Data Management SC24-5209 Terminal User's Guide concepts VS FORTRAN App. Programming: SX26-3731 VSE/VSAM Programmer's Reference SC24-5145 Source-Time Reference Sum. VSE/VSAM Documentation Subset SC24-5191 IBM FORTRAN Interactive Debug SX28- 8193 Using VSE/VSAM Commands and GC33-5382 for 05 (lSO) and VM/370 (eMS) Macros Reference Card FORTRAN IV Language GC28-6515 Q~VS .!.2M! VS FORTRAN App. programming: SC26-3985 Guide OS/VS VSAM System Information GC26-3835 VS FORTRAN App. Programming: SC26-3986 OS/VS2 Programming Library: GC26-3830 Language Reference Data Management System VS FORTRAN Installation and 5C26-3987 OS/VS VSAM Programmer's Guide GC20-3818 Customization OS/VS Service GC35-0009 VS FORTRAN App. Programming: SC26-3988 OS/VS VSAM Planning Guide GC26-3799 System Services Reference OS/VS VSAM Options for Advanced GC26-3819 Supplement Applications VS FORTRAN App. Programming: 5C26-3989 OS/VS Data Management GC26-3783 Library Reference Services Guide VS FORTRAN Compiler and Library: SC26-3990 OS/VS Access Method Services GC26-3836 Diagnosis OS/VS Planning and Use Guide GC24-5090 OS/VS2 Access Method Services GC26-3841 Planning for Enhanced VSAM under GC26-3842 OS/VS

PLII Note: "IEM OS Full American Naticnal standard COBOL" has been abbreviated to "OS OS and DOS PI/I opt. Compilers: SC26-3911 ANS COBOL" in the following list. Extended Graphic Character Set Support Supplement as PIjI Optimizing Compiler, SC33-0006 OS ANS COBOL Language Manual GC28-6396 Programmer's Guide OS ANS COEOL Compiler and SC28-6456 OS PIjI Optimi2ing Compiler, SC33-0027 Library, Version 4, Messages Programmer's Guide as PIjI Optimi2ing Compiler SC33-0026 OS ANS COBOL Installation 5C28-6458 Installation Reference Manual OS PIjI Optimi2ing Compiler SC33-0037 OS ANS COBOL Messages, Version 4 SC28-6457 CMS User's Guide OS ANS COBOL Version 4 Planning SC28-6431 OS TSC PL/I Optimizing ComFiler SC33-0029

42 IBM VMjSP Introduction OS PL/I Cptimizing Compiler GC33-0001 VM/Pass-Through Facilit~ General Information OS PL/I Checkout Compiler: GC33-0003 VM/Pass-Through Facility GC24-5206 General Information General Information Guide OS PL/I Checkout Compiler 5C33-0007 VM/Pass-Through Pacility 5C24-5208 Programmer's Guide Guide and Reference OS PL/I Language Reference GC33-0009 Manual OS PL/I Checkout Compiler 5C33-0034 .YUill Displg'y Ma!!2.9~nt System for CMS Messages OS PL/I Checkout Compiler 5C33-0031 VM/370 Display Management System GC24-5197 Installation for CMS General Information Guide OS PL/I Checkout Compiler TSO 5C33-0033 VM/370 Display Management System SC24-5198 User's Guide for CM5 Guide and Reference OS PL/I Checkout Compiler, 5C33-0047 CMS User's Guide DOS PL/I optimizing compiler 5C33-0020 VMLSP .fiSCS l!~!.!orkin.9 Installation DOS PL/I optimizing Compiler GC33-0008 VM/SP Remote Spooling GH24-5004 Programmer's Guide Communications Subsystem Networking DOS PL/I Optimizing Compiler 5C33-0051 General Information Guide CMS User's Guide VM/SP Remote Spooling SH24-5005 DOS PL/I optimizing Compiler 5C33-0021 Communications Subsystem Networking Messages Program Reference and Operations DOS PL/I Resident Library GC33-0017 Guide Program product Specifications DOS PL/I Transient Library GC33-0018 Program product Specifications OS/V5 Linkage Editor and Loader GC26-3813

VS APL: Terminal User's Guide 5H20-9067 VM/Directory 12aintmlgl!£§ for CMS VM/370 Directory Maintenance VS APL for CMS: Writing 5H20-9068 Guide for General Users SC20-1839 Auxiliary Processors Installation and System SC20-1840 VS APL: Reference Summary 5126-3712 Administration Guide VS APL: Installation Reference 5B20- 9065 Material VS APL: General Introduction GH20-9064 tos.L!.§ BPQ II APL Language Reference GC26-3847 DOS/VS BPG II Installation Reference 5C33-6122 Language SC33-6031 ~ Extension User's Guide SC33-6074 VM/SP IPCS Extension General GC34-2019 Information Guide DOSL1~ SortL~§~.9§ VM/SP IPCS Extension User's Guide SC34-2020 DOS/V5 sort/Merge Version 2 and Reference Installation Reference SC33-4045 programmer's Guide SC33-4044

V~/Interactive File Sharing GC24-5195 General Information Guide VM/Interactive File Sharing 5C24-5196 Guide and Reference

Appendix B: Related Publications for CMS Users and Other Applications 43 44 IBM VM/SP Introduction Index

A files access format 29 mode 28 structure 29 to real processor 17 system 28 accounting, virtual machine 14 IEM programs executable under 30 affinity, description of 12 language processors 30 allocating, page frames 11,17 nucleus 27 alternating operating systems 31 shared segment of 27 AP (~~ attached processor) storage size 27 applications support batch 10 of disks 28 programming 9 of tapes 27 VM/SP 9 of unit record devices 27 interactive use 9 system disk 28 operations 9 read-only 27 assembler, VM/370 30 read/write 27 attached processor user disk 28 disabling the 24 user files 28 support of 2q VIi SP-related publications 41 CMS commands 30 control 31 EDIT 31 B CMS component 27 backup 10 CMS editor, using 30 batch CMS HELP facility 29 applications 10 CMS relatEd publications 41 facility (se~ CMS Batch Facility) 32 CMS tape label processing 31 virtual machine 32 command language, CMS 29 batch systems, supported 8 command names~ synonyms 29 block multiplexer channel mode 21 commands (§gg 2122 CMS commands and CP bypass commands) shadow tables for V=R 13 commands displayed, CMS HElP 29 shadow tables for V=V 13 communication facility, virtual machine 15 byte multiplexer mode 21 communications, remote spooling 33 compilers executable under CMS 30 component of VIi/SP C CMS 1,27 channel, dedicated assignment 21 CP 1,17 channel-to-channel adapter of VM/370 attached 21 IPCS 1 virtual 7 RSCS 1 CMS (§~ CMS (Conversational Menitor components, of VM/SP 1 system) ) configuration, of CMS virtual machine 27 CMS (Conversational Monitor system) 1 console Batch Facility 32 single console image facility 4 command language 29 SNA 4 commands (§~ CMS commands) console spooling 22 configuration 27,28 control commands, CMS 31 debugging facilities 32 control units, virtual transmission 6 description of 27 conversational, user, definition of 17 disk, support 28 Conversational Monitor System (~CMS EDIT command 31 (Conversational Monitor System» Editor 31 conversion, of operating system 9 EXEC, processors 29 CP (B~ CP (Centrol program» EXEC and EXEC 2, procedures 29 CP (Control program) 1 file identification 28 description 17 file system 28 privilege class descriptions 22

Index 45 CP commands 22 EXEC general users 22 procedures, of CMS 29 INDICATE 13 processors, of CMS 29 MONITOR 13 Extended Control-program Support for VM/310 other users 24 (ECPS:VM/310) 11 CP component 11 CP execution, virtual machine's I/C 20 creating a virtual machine 1 creating manuscripts, under SCRIPT/VS 31 F· favored execution, description of 12 file structure, of CMS 29 D system, of CMS 28 DASD, temporarily defined 20 file identification, CMS 28 DASD linkage, journalling of 8 tileid 28 DASD shared, access mode 20 filemode 28 DASD sharing 20 filename 28 debugging facilities, CMS 32 files dedicated channel, device and address CMS 28 translation 21 identification 28 developing programs 9 filetype 28 device, paging 11 first level storage 18 devices fm (~~ filemode) dedicated 5 fn (~~ filename) logical 5 ft (~~~ file type) virtual, unit records 6 virtual I/O 5 DIAGNOSE interface 21 used by CMS 21 G directory general user 22 entry generating, system 9 password 1 privilege class 22 size of virtual storage 11 user identification 1 H file, VM/SP 1 handshaking, VM/VS 13 user content 1 hardware assist (§g~ virtual machine virtual device definition 20 assist, ~~ s!§£ ECPS:VM/310) discontiguous segment, shared. 21 HELP, CMS facility 29 disk initialization program 29 disks read-only 21 read/write 21 I real 6 IBM program products, executable under CMS support, CMS 28 30 system 21 identification, user (userid) 1 user 21 inactive pages 11 virtual 6 INDICATE command 13 display inhibiting display of password 8 devices, editing at 31 initialization and dump/restore program 29 of password, inhibiting 8 input, spool files 21 displayed commands and messages, CMS HELP input/output (~~ I/O) 29 integrated emulators 30 displaying performance data 13 inter user-communication vehicle (IUC~ 15 dynamic SCP switching 12 interacti ve system multiple-access 9 single user 8 E use, VM/SP applications 9 ECPS:VM/310 11 interactive problem control system (IPCS), editing files at display terminals 31 component of VM/310 35 Editor, CMS 31 Interactive Problem Control System (IPCS) editors, CMS 30 Extension Program Product 35 emulators 30 interactive problem control systems 35 integrated, that execute under VM/SP 30 35 error Inter-User Communication Vehicle (IUCV), analysis 13 overview of function 25 recording 13 invoking, operating system 8

46 IBM VM/SP Introduction I/O, operations 21 N I/O devices, virtual 5 named systems I/O error recovery, responsibility 20 creation 19 I/O handling protected 19 cylinder fault 20 unprotected 19 MSS volumes 20 native mode,SCP switching 12 I/O programs, dynamically modified 20 network, remote spooling 33 I/O request, virtual machine 20 nonconversational user, definition of 17 IPCS (§~~ IPCS (Interactive Problem Contrel nondisruptive transition to and from native System) ) 12 IPCS (Interactive Problem Control System) nonpreferred paging area 18 1 nonprogrammable remote stations 33 considerations 35 nonstandard tape label support 31 operation 35 normal storage size 17

J o journaling 8 online display of commands and messages, security 8 CftS HELP 29 operating systems alternating 31 invoking 8 L loading 8 language processors 30 supported executable under CMS 30 batch 8 languages, programming, available with CMS description of 8 30 multiple-access 8 limitations, IPCS component of VM/310 35 single-user 8 LINK command, to share DASD 20 use of multiple consecutive 9 linkage attempts, journalling 8 virtual machine 18 loading, operating system 8 operations, applications 9 locked pages, description of 11 output, spool files 22 logging on, VM/SP 7 logical devices 5 logon, procedure, VM/SP 7 logon attempts, journalling 8 P page frames description of 17 M real storage 18 maintenance support, shadow tables 12 reserved 11 Mass storage System (MSS) 5 tatle, shadow 19 volumes 5 page management, shadow tables 12 maximum storage size 17 paging 17 messages displayed, CMS HELP 29 device 17 minidisk, sharing 20 operations 18 minidisks 6 requirements 11 description of 6 paging area initializing 29 nonpreferred 18 I/O handling 20 preferred 18 mode, batch 10 password 1 MONITOR command 13 inhibiting display 8 MSS (~~ Mass storage System (MSS» performance MSS cylinder fault processing 20 analysis, description of 13 MSS I/O handling 20 collecting data 13 multiple, operating systems, consecutive displaying data 13 use of 9 factors that influence 10 multiple shadow table support 12 measurement, description of 13 multiple-access systems 9 options, list of 11 supported 8 multiprocessor support (MP) 24

Index 47 performance option discontiguous, segments 14 affinity 12 systems 14 extended'control-program support 11 SCRIPT/VS 9 favored execution 12 using 31 locked pages 11 second level storage 19 priority o~tion 12 security, of password 8 reserved page frames 11 segment virtual=real 11 description of 17 virtual machine assist 11 discontiguous saved 14 preferred paging area 18 table 17 priority option, description of 12 segment sharing, effects on page management private segments 19 19 privilege, classes 22 segments l§.g~ shared segments) problem report data collection 3~ selective invalidation, shadow tables 12 processor selector channel mode 21 attached, using 24 shadow page table 19 virtual, brief description 4 shadow table 19 processor mode, single 12 bypass for V=R 13 program bypass for V=V 13 compilation commands, CMS 30 shadow tables, maintenance support 12 develc~ment 9,30 shared development and execution 29 segment, protection 14 execution 30 systems 14 execution commands, CMS 30 shared segments program ~roducts, recommended 1 creation of 19 programmable operator Facility protected 19 introduction 15 types 19 description 25 unprotected 15 programmable remote stations 33 sharing programming segments 14,27 applications 9 systems 14 languages, available with CMS 30 single console facility 4 systems 9 single processor mode 12 protected named systems- 19 single user systems 9 violation 19 single-user systems, supported 8 protection, shared segment 14 SNA (system network architecture) virtual publications console 4 CMS related 41 spool files compilers used in VM/370 and VM/SP input 21 environments 41 output 22 relating to other applications 41 spooling VM/SP options 22 for CMS users 41 remote 22 relationship of audience to remote communications 33 publication 37 unit record I/O 21 virtual console I/O 22 standard tape label support 31 storage R management of 17 real disks mappings 12 description of 6 of virtual machine 17 partitioned into minidisks 6 si2e real storage, page frame 18 defining 17 recommended program products 1 maximum 17 remote spooling 22 normal 17 remote spooling communication 33 virtual, trief description 3 Remote Spooling Communications Subsystem storage management, shadow tables 12 (RSCS) Networking 33 support, of system 9 remote stations 33 swit~hing to and from native mode 12 reserved page frames, description cf 11 system RSCS (Remote Spooling Communications attached processor 24 Subsystem) 1 backup 10 running multiple partitions 8 generation 9 support 9 support for, attached Frocessor (AP) 24 testing 9 S system console, virtual 4 saved system recovery, multiprocessor 24

48 IBM VM/SP Introduction system ~eguirements (see Virtual virtual devices, definition 20 Machine/System Product requirements) virtual lines 6 systems virtual machine programming 9 accounting 14 saved 14 communication facility 15 shared 14 concept 2 System/370 Extended support 13 I/C reguest 20 mini disk I/O handling 20 usage example 3 virtual machine assist, description of 11 T virtual machine communication facilitj table (VMCP), overview of function 24 page 17 Virtual Machine Facility/370, assembler 30 segment 17 virtual machine I/O, CP execution 20 shadow 19 virtual machines tape latel processing 31 configuration, for CMS 2~ Teu (§~ transmission control unit) creation 7 T-disk space 6 description 1 termination, saving virtual sto~age 18 m·ultiple 8 testing, of system 9 operating systems 18 third level storage 19 running concurrent production, time, management 17 development, and testing 9 time sharing 27 storage 17 time slice 17 storage management 17 time slicing 17 time management 17 time-sharing 9 Virtual Machine/System Product Trace Table Recording Facility composition of 1 introduction 15 cont~ol program 17 description 25 directory 7 transferring, files 22 publications for eMS users 41 transfer~ing files, via a remote spooling Virtual Machine/System Products comFonents network 33 1 typical CMS configuration 28 virtual storage first level, definition of 18 second level, definition of 19 size of 17 u . third level, definition of 19 unit re~brd devices, virtual 6 virtual storage preservation 18 unprotected named systems, elimination of virtual transmission, control units 6 overhead 19 virtual unit record devices, description of unprotected shared segments 15 6 user / VMCF (§~ Virtual Machine Communication conversational, definition of 17 Facili tj) disk, eMS 28 VM/SP, composition of 1 general 22 VM/SP applications 9 identification 7 interactive use 9 nonconversational, definition of 17 operations 9 user directory (~VM/SP directory) backup 9 user directory 2 system generation 9 user files, CMS 28 system support 9 userid 7 system testing 9 VM/SP directory 2 (~~~ user directory) VM/SP extended control-program support V (ECPS: VM/370) 11 V=R, shadow table bypass 13 VM/SP publications, relaticnship to V=V, shadow table bypass 13 audience 37 virtual VM/SP system/370 Extended support 13 channel-to-channel adapter 7 VM/VS handshaking 13 devices, dedicated 19 volumes, MSS 5 disks 6 I/O devices 5 processor, b~ief description 4 W system console 4 wait state, of virtual machine 17 unit reco~d devices 6 virtual=real description of 11 3 option 11 370E support 13

Index 49 GC19-6200-1

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