z/OS 2.4 DFSMS Using Data Sets IBM SC23-6855-40 Note Before using this information and the product it supports, read the information in “Notices” on page 591. This edition applies to Version 2 Release 4 of z/OS (5650-ZOS) and to all subsequent releases and modifications until otherwise indicated in new editions. Last updated: 2021-04-06 © Copyright International Business Machines Corporation 1987, 2021. US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Figures............................................................................................................... xix Tables................................................................................................................xxv About this document......................................................................................... xxix Major divisions of this document.............................................................................................................xxix Required product knowledge.................................................................................................................. xxix Referenced documents............................................................................................................................ xxx z/OS information.......................................................................................................................................xxx How to send your comments to IBM................................................................... xxxi If you have a technical problem.............................................................................................................. xxxi Summary of changes....................................................................................... xxxiii Summary of changes for z/OS Version 2 Release 4..............................................................................xxxiii Summary of changes for z/OS V2R3..................................................................................................... xxxiv Summary of changes for z/OS V2R2..................................................................................................... xxxiv Part 1. All data sets............................................................................................... 1 Chapter 1. Working with data sets...............................................................................................................3 Data storage and management..............................................................................................................3 System-managed data sets.............................................................................................................. 4 Distributed FileManager....................................................................................................................4 Access methods..................................................................................................................................... 4 Basic Direct Access Method............................................................................................................. 4 Basic Partitioned Access Method..................................................................................................... 4 Basic Sequential Access Method......................................................................................................5 Data-in-Virtual (DIV)......................................................................................................................... 5 Indexed Sequential Access Method.................................................................................................5 Object Access Method...................................................................................................................... 6 Queued Sequential Access Method..................................................................................................6 Virtual storage access method......................................................................................................... 6 Access to z/OS UNIX files................................................................................................................. 7 Selection of an access method.........................................................................................................8 Direct Access Storage Device (DASD) volumes..................................................................................... 8 DASD labels.......................................................................................................................................8 Track format...................................................................................................................................... 8 Track overflow...................................................................................................................................9 VSAM record addressing...................................................................................................................9 Actual and relative addressing with non-VSAM access methods................................................. 10 Magnetic tape volumes........................................................................................................................ 11 Using magnetic tape labels............................................................................................................ 11 Specifying the file sequence number.............................................................................................11 Identifying unlabeled tapes............................................................................................................13 Using tape marks............................................................................................................................ 14 Data management macros...................................................................................................................14 Data set processing..............................................................................................................................15 Allocating data sets........................................................................................................................ 15 iii Processing data sets through programs.........................................................................................16 Using access methods.................................................................................................................... 16 Using addressing modes.................................................................................................................16 Using hiperspace and hiperspace.................................................................................................. 17 Processing VSAM data sets............................................................................................................ 17 Processing PDSs, PDSEs, and UNIX directories.............................................................................18 Processing sequential data sets and members of PDSEs and PDSs.............................................18 Processing UNIX files with an access method...............................................................................19 Processing EXCP, EXCPVR, and XDAP macros...............................................................................20 Processing data sets on read-only devices....................................................................................20 Distributed Data Management (DDM) attributes.................................................................................23 Virtual I/O for temporary data sets......................................................................................................23 Data set names.....................................................................................................................................24 Catalogs and volume table of contents............................................................................................... 25 VTOC................................................................................................................................................25 Catalogs...........................................................................................................................................25 Data set names and metadata....................................................................................................... 25 Security of data set names............................................................................................................. 26 Chapter 2. Using the Storage Management Subsystem........................................................................... 27 Using automatic class selection routines............................................................................................ 28 Allocating data sets..............................................................................................................................29 Allocating data sets with JCL..........................................................................................................30 Allocating system-managed data sets with the Access Method Services ALLOCATE command..................................................................................................................................