PK27705: S0C4 AT OFFSET, DATA NOT KEY COMPRESSION USED, INTERMITTENT PROBLEM.

APAR status

• Closed as program error.

Error description

• S0C4 at offset, data not key compression used, intermittent
  problem.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All HSDCE users who run the tool on a z900   *
  *                 (Freeway) machine.                           *
  ****************************************************************
  * PROBLEM DESCRIPTION: The customer was using an IMS reload    *
  *                      utility that passed the exact segment   *
  *                      length to the IBM HSDCE compression     *
  *                      exit.                                   *
  *                      The standard IMS interface passes the   *
  *                      segment length PLUS a few bytes for     *
  *                      overflow protection.                    *
  *                      The exact (and correct) segment length  *
  *                      passed by the reload utility caused an  *
  *                      ABENDS0C4 to occur in the CMPSC         *
  *                      microcode invoked by the exit.          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The CMPSC instruction was changed from pure microcode to an
  implementation using Hardware Assist (Compression Unit, a.k.a.
  CoP-Unit) with the introduction of the z900 (Freeway) machine.
  The Freeway long operands (Length > 1 Page) process includes
  a lookahead of one page to ensure that no access exceptions
  occur during processing. The pre-Freeway implementation does
  not perform this lookahead.
  The HCOZLDX0 compression exit driver passed an invalid length
  (2 bytes more than were needed) to the CMPSC instruction.
  This has not caused a problem before, because the lookahead,
  when invoked directly from IBM's interface, had sufficient
  pad bytes.
  

Problem conclusion

• HCOZLDX0 and HCOZLDXV were changed to accurately reflect the
  true segment data length.
  To implement this fix in pre-existing HSDCE compression exits
  please see the instructions in Chapter 7 of the Users Guide
  under the heading "Relinking a compression exit routine" and
  sample JCL in figure 28.
  

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:

  UK18694

Modules/Macros

•    HCOZLDXV HCOZLDX0
  

Fix information

• Fixed component name

  IMS HDCE

• Fixed component ID

  5655E0200

Applicable component levels

• R220 PSY UK18694

     UP06/10/11 P F610