PI72224: START DDF TIMING CONDITION RESULTS IN ABEND0C4 RC38 IN DSNLTDDF AND ABEND04E RC00E500705 IN DSNVEU3I.DSNVEUS3

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• DB2DDF DB2TERM DB2ABTERM
  DB2 12 for z/OS users - see PI72507.
  Customer's automations is issuing a -DIS DDF command while
  -START DDF is processing. This can result is a timing problem
  between Display DDF Detail (DSNLTDDF) and a Start DDF (DSNLIINI)
  after a prior Stop DDF, Mode(Force). The unexpected, and
  un-serialized, clearing of LCBLLQCR by Start DDF (DSNLIINI)
  processing MAY lead to the 0C4-38 in DSNLTDDF (on the
  "MVCP(XLCL_LQCRELEM,XPTR->LQCRELEM,GR2);" instruction). DSNLTDDF
  recovery does get control but it doesn't release the latch
  since LCBLLQCR got zeroed by Start DDF (DSNLIINI) processing.
  DSNLTDDF recovery can't release the latch because the LQCRHEAD
  control block itself was freed by DSNLIINI and hence the
  LQCRLTCH latch is no longer available to be released. The
  apparent un-released latch is detected by DSNVEUS3 (non zero
  EBLTCHLD) via 04E-00E50705 and this ultimately causes the
  subsystem to be terminated with DSNV086E 00E50705.
  ***************************************************************
  Additional Symptoms and Keywords:
   ABEND0C4 AB0C4 S00C4 0C4
    0C4-00000038 00000038 RC00000038 RC38
     DSNLTDDF DSNLTDDF+0698 0698 OFFSET0698
    0C4-00000011 00000011 RC00000011 RC11
     DSNLDUMP DSNLDUMP+0326 0326 OFFSET0326
   ABEND04E AB04E S004E 04E
    04E-00E50705 00E50705 RC00E50705
     DSNVEUS3 DSNVEUS3+1560 1560 OFFSET1560
   ABEND04F AB04F S004F 04F
   MSGDSNV086E DSNV086E 00E50705 RC00E50705
  

Local fix

• Customer is advised not to issue -DIS DDF DET until -START DDF
  has fully completed
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Distributed Data Facility (DDF) users.   *
  ****************************************************************
  * PROBLEM DESCRIPTION: Abend 0C4-00000038 DSNLTDDF+0698        *
  *                      followed by 04E-00E50705 DSNVEUS3+1560  *
  *                      and a DB2 subsystem termination with    *
  *                      message DSNV086E 00E50705.              *
  *                      The condition is intermittent and only  *
  *                      occurs when DDF is being restarted      *
  *                      after a prior stop DDF (force or        *
  *                      quiesce) and a DISPLAY DDF DETAIL       *
  *                      command quickly occurs while DDF is     *
  *                      restarting.                             *
  *                      LOGREC may also show evidence of abend  *
  *                      0C4-00000011 DSNLDUMP+0326 if DDF was   *
  *                      previously force stopped.               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The user stops DDF via the STOP DDF (force or quiesce) command.
  The user then restarts DDF via the START DDF command but also
  enters a DISPLAY DDF DETAIL command at the same time.
  Start DDF processing must clean-up some resources that remained
  after the previous DDF instance was stopped. A timing condition
  exists between this START DDF clean-up processing and DISPLAY
  DDF DETAIL command processing. This timing condition may lead
  to abend 0C4-00000038 DSNLTDDF while DISPLAY DDF DETAIL
  processing is accessing resources that START DDF processing is
  freeing. The nature of the condition prevents a latch from
  being freed (during DISPLAY DDF DETAIL abend recovery
  processing). The unexpected presence of the latch leads to
  04E-00E50705 DSNVEUS3 and a subsystem termination with message
  DSNV086E and reason 00E50705.
  An 0C4-00000011 DSNLDUMP abend may also be observed, in LOGREC
  only, during dump processing for the initial 0C4-00000038
  DSNLTDDF abend, but only if the previous instance of DDF was
  stopped force. This DSNLDUMP abend occurs because a resource
  reference (from the prior instance of DDF) remained after the
  prior stop force but was not cleared during start processing
  even though start processing freed the resource (prior to
  refreshing it).
  Users can avoid the condition during DDF start processing by
  either not issuing the DISPLAY DDF DETAIL command or by issuing
  the DISPLAY DDF (without DETAIL) command instead.
  

Problem conclusion

• DB2 DISPLAY DDF DETAIL command processing has been changed to
  consider being driven while DDF start processing is cleaning up
  resources left from a prior instance of DDF.
  DB2 start DDF processing has been changed to clear a resource
  reference (from a prior DDF instance) before the resource is
  freed.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  PI72507 UI43097 UI43098

Modules/Macros

• DSNLSSST DSNLTDDF
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UI43097

     UP16/12/20 P F612 Ž

• RB10 PSY UI43098

     UP16/12/20 P F612 Ž

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.