Intro to z/OS Steve Warren IBM November 2020 Session 5AO Introduction • This presentation will cover (at the 50,000 foot level) many different areas (but not all) of z/OS • Don’t be overwhelmed. There is a ton of material here. The purpose of this session is to acquaint you with some of the major concepts of z/OS z/OS Concepts #CC 2 Agenda Why Z Matters and Why z/OS z/OS UNIX/ISHELL/OMVS/Remote Hardware/LPAR Address Spaces & Modes z/OS Components Storage & DAT Software Stack Batch Processing/JES/JCL App Dev, App Exec and Mgmt Envs SDSF DASD Job Flow Data Sets / Allocation System Log PDS & PDSE IPL VTOC & Catalogs Sysplex/GDPS SMS Serialization TSO/E Managing Workloads ISPF z/OS Concepts #CC 3 Why Z Matters? 4 Why Z Matters Utilities Retail Government Financial Healthcare Travel Telecoms Automotive Weather z/OS Concepts #CC 5 Why Z Matters Mainframes process 30 billion business transactions per day Mainframes process 1.3 million CICS transactions. Every second. Every day. Mainframes enable $6 trillion in card payments annually 80 percent of the world’s corporate data originates on mainframes 91 percent of CIOs said new customer- facing apps are accessing the mainframe z/OS Concepts #CC 15 Why z/OS? • Ideally suited for processing large workloads for many concurrent users • Highest security ratings for an OS • Highest reliability • Low TCO compared to other enterprise competitors • Designed for: • Serving 1000s of users concurrently • I/O and numeric intensive computing • Processing very large heterogeneous workloads • Running mission critical applications securely z/OS Concepts #CC 16 Naming of OS 17 z/OS Lineage • At the beginning there was: • OS/360 (1966) • Configuration options PCP, MFT and MVT • OS/VS2 R1 (~1972) Since 2001 the name • Retroactively renamed to SVS has remained z/OS • OS/VS2 R2 (~1974) • Also called MVS • MVS/370 (~1977) • MVS/SP V1 • Optionally DFDS and DFEF • MVS/XA (1983) • MVS/SP V2 or V3 and MVS/DFP • MVS/ESA (~1990) • MVS/SP V4 or V5 This is the longest • Either MVS/DFP or DFSMS/MVS that it has been called • OS/390 (1996) one name! • z/OS (2001) z/OS Concepts #CC 18 Hardware Context of z/OS 19 IBM Z Server – the IBM z15 z/OS Concepts #CC 20 IBM Z Server – Multiple LPARs Each LPAR can Up to 85 be allocated LPARs can be different defined amounts of resources (up to 16TB memory) LPAR LPAR LPAR LPAR LPAR LPAR LPAR PR/SM™ CP, Memory, I/O Support Element (SE) z/OS Concepts #CC 21 IBM Z Hardware and z/OS CFCC z/OS® – z/TPF z/OS® z/VSE® ICF Linux on z Systems® Linux on z Systems® Linux on z Systems® Linux on z Systems® z/VM® PR/SM™ z/OS (a.k.a. Multiple VirtualCP, Memory, I/O Storage - MVS)Support Element (SE) Where we will be spending our z/OS Concepts time #CC 22 z/OS Elements, Features, and Components 23 z/OS Concepts – Elements, Features, Components • z/OS is a collection of elements • Each element consists of a collection of modules (called components) Examples: IOS, RSM, GRS, Contents, Allocation, Consoles, NIP, Scheduler, SMF, BCPii, Logger z/OS Concepts #CC 24 z/OS Concepts – Elements, Features, Components • z/OS is a collection of elements • Each element consists of a collection of modules (called components) • Base elements are always included in z/OS • BCP (Base Control Program) • DFSMSdfp (Data Facility Storage Management Subsystem) • Deliver essential operating system functions Other Base Elements: Communication Server, z/OSMF, HLASM, TSO, ISPF, JES2, Metal C Runtime Library z/OS Concepts #CC 25 z/OS Concepts – Elements, Features, Components • z/OS is a collection of elements Optional Features • Each element consists of a collection of modules (calledExamples: components) • Base elements are always included in z/OS Security Server, SDSF, • BCP (Base Control Program) XL C/C++, RMF, JES3, • DFSMSdfp (Data Facility Storage Management Subsystem)DFSMShsm, DFSMSdss • Deliver essential operating system functions • Optional features installed in addition to base elements • Requested separately from base elements • Can be priced or free z/OS Concepts #CC 26 Software Stack 27 IBM z/OS Software Stack Applications Middleware z/OS® Operating System Provides critical set of system services made possible by the z/Architecture® and firmware z/OS Concepts #CC 28 IBM z/OS Software Stack Applications Middleware Software that is z/OS® neither operating Operating System system code nor an end-user application z/OS Concepts #CC 29 IBM z/OS Software Stack Applications Middleware z/OS® Db2® OperatingData Base System 2 CICS® Customer Information Control System IMS™ Information Management System WAS WebSphere® Application Server IBM MQ IBM Message Queuing SAP® Systems, Applications and Products in Data Processing TSO/E Time Sharing Option/Extensions SAP is the registered trademark of SAP SE in Germany and in several other countries. z/OS Concepts #CC 30 IBM z/OS Software Stack Applications Provide end-user interface to product Middleware solutions z/OS® Operating System ISPF Interactive System Productivity Facility SA z/OS IBM System Automation for z/OS z/OS Concepts #CC 31 Application Development Environments, Application Execution Environments and z/OS Management Environments 32 Application Development Env z/OS supports many programming languages as well as modern IDEs and environments z/OS Concepts #CC 33 Application Development Env z/OS supports many programming languages as well as modern IDEs and environments • Assembler • COBOL • C/C++ • PL/I • Fortran • REXX • JAVATM • Python • Node.js • Scala z/OS Concepts #CC 34 Application Development Env Legacy interactive interface z/OS Concepts #CC 35 Application Development Env Integrated Development Legacy interactive interface Environment (IDE) z/OS Concepts #CC 36 Application Development Env Integrated Development Other Modern Application Legacy interactive interface Environment (IDE) Development Tools z/OS Concepts #CC 37 Application Development Env z/OS Concepts #CC 38 Application Execution Env Traditional z/OS z/OS UNIX application application environments, environment including middleware Java Virtual Machine z/OS Container Extensions application environment #CC application environment z/OS Concepts 39 Management Environments z/OS Management Facility (z/OSMF) provides modern interface to help manage your z/OS systems z/OS Concepts #CC 40 DASD 41 IBM Speak – DASD • DASD – Direct Access Storage Device • Think “Hard Drive” z/OS Concepts #CC 42 IBM Speak – DASD • DASD – Direct Access Storage Device • Think “Hard Drive” • a.k.a. DASD Volume • Volume needs a label • Volume Serial Number (VOLSER) • 1 to 6 characters z/OS Concepts #CC 43 Data Sets 44 IBM Speak – Data Set • Data set • Think “File” • Contains data in different structured formats • Need to choose the format of data set and reserve space (allocate dataset) prior to using for the first time • Resides on DASD, Tape • z/OS has types of data sets • Legacy Data set • Unix file IBM prefers the spelling “data set” to “dataset” z/OS Concepts #CC 45 IBM Speak – Data Set DSORG=PS (Physically Sequential) Data Editing the data set gives you all the data in the data set z/OS Concepts #CC 46 IBM Speak – Data Set DSORG=PS (Physically Sequential) Data DSORG=PO (Partitioned) Directory Member 1 Data Member 2 Data Member 3 Data The PDS contains a directory to locate the members z/OS Concepts #CC 47 PDS & PDSE • PDSE data sets can be used in place of nearly all PDS data sets • PDSE designed to address running out of space issues • Compression is not necessary • PDSE directory expands to fit the members z/OS Concepts #CC 48 IBM Speak – Data Set Name • Data set name (DSN or DSName) • Think “File Name” z/OS Concepts #CC 49 IBM Speak – Data Set Name • Data set name (DSN or DSName) • Think “File Name” • 1 to 22 segments • segments separated by a period • each segment limited to 8 characters FRED.ASSEMBLE.SOURCE z/OS Concepts #CC 50 IBM Speak – Data Set Name • Data set name (DSN or DSName) • Think “File Name” • 1 to 22 segments • segments separated by a period • each segment limited to 8 characters • Up to 44 characters (includes periods) • High-level qualifier (HLQ) is typically your userid High-level Low-level qualifier qualifier (HLQ) FRED.ASSEMBLE.SOURCE z/OS Concepts #CC 51 Data Set Allocation 52 IBM Speak – Data Set Allocation • Data set allocation • Think “Create Space” for a data set on disk z/OS Concepts #CC 53 IBM Speak – Data Set Allocation • Data set allocation • Think “Create Space” for a data set on disk • Need: • Data set name • VOLSER (i.e., the DASD volume) where the space should be allocated • Data set attributes (Size, RECFM, LRECL, BLKSZE, DSORG) z/OS Concepts #CC 54 VTOC and Catalogs 55 IBM Speak – VTOC & Catalogs Allocate space for data set FRED.ASSEMBLE.SOURCE on volume VOL100 FRED.ASSEMBLE.SOURCE VOL100 VOLSER z/OS Concepts #CC 56 IBM Speak – VTOC & Catalogs DASD volume has a Volume Table of Contents (VTOC) that locates a data set on the volume VTOC FRED.ASSEMBLE.SOURCE VOL100 z/OS Concepts #CC 57 IBM Speak – VTOC & Catalogs To simplify find the data set, the name and location information is placed in a catalog VTOC SYS1.USERCAT FRED.ASSEMBLE.SOURCE FRED.ASSEMBLE.SOURCE is on VOL100 VOL002 VOL100 z/OS Concepts #CC 58 IBM Speak – VTOC & Catalogs There can be many catalogs so how do we locate the correct one? VTOC SYS1.USERCAT FRED.ASSEMBLE.SOURCE FRED.ASSEMBLE.SOURCE is on VOL100 VOL002 VOL100 z/OS Concepts #CC 59 IBM Speak – VTOC & Catalogs We look in the “Master” catalog (of which there is only one) VTOC SYS1.MSTRCAT SYS1.USERCAT FRED.* data sets cataloged in FRED.ASSEMBLE.SOURCE FRED.ASSEMBLE.SOURCE SYS1.USERCAT