PH04329: HDCE COMMON STORAGE OVERLAY

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• IMS Tools HD Compression Extended causes common storage
  overlay when unexpected compressed segment is passed.
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM IMS Tools Base for z/OS     *
  *                 Version 1 Release 6 (FMID: HAHN160) who use  *
  *                 IMS Hardware Compression Extended.           *
  ****************************************************************
  * PROBLEM DESCRIPTION: Common storage overlay while expanding  *
  *                      a segment with DBPCB PROCOPT=GO.        *
  ****************************************************************
  * RECOMMENDATION: Apply the maintenance for this APAR.         *
  ****************************************************************
  This APAR fixes the following problems in IBM Tools Base
  Hardware Data Compression Extended:
  1. Common storage overlay while expanding a segment with DBPCB
     PROCOPT=GO
    When PROCOPT=GO is specified in DBPCB of a program which
    retrieves compressed segments, the contents of segment data
    passed by IMS for expansion may not be exactly same as when
    it was compressed. In this situation, HD Compression
    Extended may destroy common storage beyond the size provided
    by IMS.
  2. Eliminating redundant serialization
    Process serialization is always performed although it is only
    required when hardware compression call (CMPSC) instruction
    is not supported, which should available with current IBM
    zServers.
  

Problem conclusion

• IBM Tools Base Hardware Data Compression Extended has been
  changed to fix the problems:
  1. Before expanding a compressed segment, HD Compression
    Extended validates the segment data length and returns error
    condition to IMS if it is inconsistent. This can prevent
    possible storage overlay.
  2. When returning to IMS after initialization, if hardware
    compression instruction is available with the system, HD
    Compression Extended indicates IMS that serialization is not
    required since it is needed only with software compression
    service. This can eliminate serialization by IMS and improve
    both CPU and elapsed time.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI59894

Modules/Macros

• HCOZLDX0 HCOZLDXV
  

Fix information

• Fixed component name

  TOOLS BASE

• Fixed component ID

  5655V9300

Applicable component levels

• R160 PSY UI59894

     UP18/11/27 P F811

Fix is available

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