GC26-3875-0 OS/VS2 MVS Data Management Services Guide
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GC26-3875-0 File No. S370-30 Systems OS/VS2 MVS Data Management Services Guide Release 3.7 Includes the Following Selectable Units: Data Management VS2.03.808 3800 Printing Subsystem VS2.03.810 System Security Support 5752-832 PREFACE This book describes all IBM data management except for VSAM (virtual storage access method) and specialized applications such as the time sharing option (TSO), graphics, teleprocessing, optical character readers, optical reader-sorters, and magnetic character readers. These specialized applications are described in separate publications that are listed in IBM System/370 Bibliography,GC20-0001. To learn about VSAM or to write programs that create and process VSAM data sets, refer to: • Planning for Enhanced VSAM Under OS/VS, GC26-3842, which introduces VSAM and describes its concepts and functions. • OS/VS Virtual Storage Access Method (VSAM) Programmer's Guide, GC26-3838, which describes how to create VSAM data sets and code the macro instructions required to process them. • OS/VS2 Access Method Services, GC26-3841, describes the service program commands used to manipulate VSAM data sets. • OS/VS Virtual Storage Access Method (VSAM) Options for Advanced Applications, GC26-3819, which describes-applications not required in the normal use of VSAM. If you know how to write assembler-language programs and use job control statements, you can use this book and OS/VS2 MVS Data Management Macro Instructions, GC26-3873, to write programs that create and process data sets. To use this book you must have basic knowledge of the operating system as contained in OS/VS2 Release 3 Guide, GC28-0770; of assembler language as described in OS/VS—DOS/VS—VM/370 Assembler Language, GC33-4010; and of job control language (JCL) as explained in OS/VS2 JCL, GC28-0692. This book has three parts: "Part 1: Introduction to Data Management" introduces you to the characteristics of data sets, how you name them, how the system catalogs them, and how you format the records in them. The format of tracks on a direct-access storage device is explained briefly. Part 1 also describes the data control block (DCB) and the information it supplies to the operating system. Special processing routines that you specify in the DCB macro instruction are also explained in this section. In "Part 2: Data Management Processing Procedures" there is an explanation of data-processing techniques that includes the macro instructions for the queued access technique and the basic access technique and the macro instructions for analyzing input and output errors. The section on data-processing techniques also tells how to select an access method and how to begin and end processing of a data set. The section "Buffer Acquisition and Control" in Part 2 explains three different methods you can use to obtain buffers and the macro instructions you use with each method. This section also describes ways to control buffers: simple buffering for the queued access technique, direct buffering and dynamic buffering for the basic access technique. In addition, for the queued access technique, there is an explanation of the four modes of moving the records in virtual storage: move mode, data mode, locate mode, and substitute mode. Macro instructions for controlling buffers are described here, too. The next four sections of Part 2 concern processing data sets of four different types: a sequential data set, a partitioned data set, an indexed sequential data set, and a direct data set. They explain the organization of the data sets and the macro instructions used to process them. In the examples the macro instructions are coded in just enough detail Preface 3 to make the examples clear. For a complete description of the operands and options available, see OS/VS2 MVS Data Management Macro Instructions, GC26-3793. "Part 3: Data Set Disposition and Space Allocation" tells you how to figure the amount of space you need for a data set on a direct-access storage device and how to request that space in your JCL DD statement. You are given special directions for allocating space for a partitioned data set and an indexed sequential data set. Part 3 also tells how to indicate in the JCL DD statement the status of the data set at the beginning of and during processing and how to indicate what you want the system to do with the data set when processing has terminated. You also are told how to use the DD statement to route the data set to a system output writer, to concatenate data sets, to catalog data sets, and to protect confidential data sets. Appendix A describes data set labeling. Appendix B explains control characters you can use to control card punches and printers. A glossary of acronyms and abbreviations used in this book and the index follow Appendix B. The following manuals are referred to in the text. • OS/VS Message Library: VS2 System Codes, GC38-1008 • OS/VS Message Library: VS2 System Messages, GC38-1002 • OS/VS2 JCL, GC28-0692 • OS/VS2 MVS CVOL Processor, GC26-3864 • OS/VS2 MVS Resource Access Control Facility (RACF): General Information Manual, GC28-0722 • OS/VS2 Supervisor Services and Macro Instructions, GC28-0683 • OS/VS2 System Programming Library: Data Management, GC26-3830 • OS/VS2 System Programming Library: Debugging Handbook, Volume 1, GC28-0708 • OS/VS2 System Programming Library: Debugging Handbook, Volume 2, GC28-0709 • OS/VS2 System Programming Library: Initialization and Tuning Guide, GC28-0681 • OS/VS2 System Programming Library: Service Aids, GC28-0633 • OS/VS2 System Programming Library: Supervisor, GC28-0628 • OS/VS2 System Programming Library: System Generation Reference, GC26-3792 • IBM 3800 Printing Subsystem Programmer's Guide, GC26-3846 • IBM 3890 Document Processor Machine and Programming Description, GA24-3612 • OS Data Management Services and Macro Instructions for IBM 1419 / 1275, GC21-5006 • OS and OS/VS Programming Support for the IBM 3505 Card Reader and IBM 3525 Card Punch, GC21-5097 • OS/VS IBM 3886 Optical Character Reader Model 1 Reference, GC24-5101 • OS/VS Mass Storage System (MSS) Planning Guide, GC35-0011 • OS/VS Mass Storage System (MSS) Services: General Information, GC35-0016 4 OS/VS2 MVS Data Management Services Guide • OS/VS Tape Labels, GC26-3795 • OS/VS Utilities, GC35-0005 In this manual, any references made to an IBM program product are not intended to state or imply that only IBM's program product may be used; any functionally equivalent program may be used instead. This manual has references to the following IBM program products: • RACF-Resource Access Control Facility Program Number, 5740-XXH Preface 5 Page of GC26-3875-0 Revised August 31, 1978 By TNL GN26-0915 CONTENTS Preface .................................................................................................................... 3 Figures ................................................................................................................... 11 Summary Of Amendments ................................................................................... 13 Part 1: Introduction to Data Management ......................................................... 17 Data Set Characteristics ...................................................................................... 17 Data Set Identification ................................................................................... 19 Data Set Storage ............................................................................................. 19 Direct-Access Volumes ............................................................................. 20 Magnetic-Tape Volumes ........................................................................... 20 Data Set Record Formats .............................................................................. 21 Fixed-Length Records .............................................................................. 22 Variable-Length Records ..... ............ ............ ................. 24 Undefined-Length Records 30 Control Character ...................................................................................... 31 3800 Table Reference Character ....................................................................... 31 Direct-Access Device Characteristics ............................................................... 31 Track Format .................................................................................................. 32 Track Addressing ........................................................................................... 33 Track Overflow .............................................................................................. 34 Write-Validity-Check Option ........................................................................ 34 The Data Control Block .......... ...... ................ ................ ...... ......... ........ 34 Data Set Description ...................................................................................... 35 Processing Program Description .................................................................... 37 Macro Instruction Form (MACRF) ........................................................ 37 Exits to Special Processing Routines ....................................................... 38 Modifying the Data Control Block ............................................................... 53 Sharing a Data Set .......................................................................................... 54 Part 2: Data Management Processing Procedures ............................................. 59