IBM Support

Creating Compressed Format PDSEs

How To


Summary

Outline the requirement and process to enable and create a compressed format PDSE

Steps

  • The first step in creating a compressed-format PDSE data set is to have your security administrator enable the RACF discrete FACILITY class STGADMIN.SMS.ALLOW.PDSE.COMPACT.
  • Verify the existence or request the creation of an SMS DATACLAS with the COMPACTION ZP or COMPACTION ZR attribute.
    • ZR - Indicates “zEDC Required”, meaning that system fails the allocation request when the zEDC function is unavailable, or the minimum allocation amount requirement is not met. 
    • ZP - Indicates "zEDC Preferred”, meaning that the system honors the allocation request even when zEDC facilities are unavailable, or the minimum allocation amount requirement is not met.  In this situation, a noncompressed Version 2 PDSE is created.
  • Coexistence requirements: When all systems within a sysplex are at z/OS V2R3 or z/OS V2R4 system with OA61168, or at z/OS V2.R5, then support for creating compressed-format PDSE data sets is enabled.
  • Most characteristics that apply to PDSE data sets continue to apply to compressed-format PDSE data sets. The following characteristics further describe compressed-format PDSEs:
    • Compression within a compressed-format PDSE occurs at the member level.
    • A member that does not meet minimum system-determined criteria is not compressed. The minimum criteria are:
      • The member is at least 65,536 bytes. 
      • Compression does not increase the size of the member.
    • Directory entries are not compressed.
    • A member within a compressed-format PDSE cannot be opened for update.
    • While a program object can be added to a compressed-format PDSE, program objects are not compressed.  
    • A compressed-format PDSE is automatically allocated as a Version 2 PDSE regardless of the version specified on the DSNTYPE allocation parameter. 
    • A compression-format PDSE has the DS1COMPR bit set in the DS1FLAG1 field in its FMT-1 or FMT-8 DSCB.

    • These statistics are expected when using ISMF / LISTCAT

      ISMF displays ??? under COMPRESSED FORMAT Field

      ISMF displays no data under % User Data Reduction Field

      LISTCAT ENTRY displays

      ACT-DIC-TOKEN----X'FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF'    


      Other Restrictions: 
      • Compressed-format PDSE data sets must be SMS managed.
      • Temporary data sets cannot be allocated as a compressed-format PDSE data set.

Additional Information

The following job log message is seen in batch allocation jobs when the STGADMIN.SMS.ALLOW.PDSE.COMPACT facility class is not enabled:
IGD17157I DSNTYPE LIBRARY IS NOT A SUPPORTED DATA SET TYPE FOR COMPRESSION
BECAUSE STGADMIN.SMS.ALLOW.PDSE.COMPACT IS NOT DEFINED  
                   
IGD17163I COMPRESSION REQUEST NOT HONORED FOR DATA SET                     
SYSPLEX.COMPRESS.PDSE.ZR BECAUSE DATA SET                                  
CHARACTERISTICS DO NOT MEET COMPRESSION CRITERIA, ALLOCATION CONTINUES    

Document Location

Worldwide

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Document Information

Modified date:
13 September 2022

UID

ibm16587557

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