PM61521: PROVIDE A NEW QCF RECOVERAB FUNCTION FOR SHARED QUEUES ONLY

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• A current REQ is to have the possibility to re-enqueue input
  messages which, as per a MSGQ Structure full condition, were
  logged on OLDS / SLDS as unresolved UOWE and also in case IMS
  would have to be restarted with a cold start. This is based
  off of FITS REQ MR00075806.
  
  The current RECOVERAB function is for non-shared queues only.
  It starts with the last queue checkpoint and selects all
  messages that have not been de-queued.
  The new RECOVERAB will be used when shared queues IMS cannot be
  /ERE started and needs to be COLD started. The messages that are
  in the logs that did not make their way to the CQS will be
  selected (not all messages in and after the last queue
  checkpoint as it is in the current RECOVERAB function).
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of QCF 3.1 with shared queues. This    *
  *                 APAR provides RECOVERAS procedure for shared *
  *                 queues.                                      *
  ****************************************************************
  * PROBLEM DESCRIPTION: In shared queues environment:           *
  *                       - IMS writes x'67D0' log records for   *
  *                      messages that can not be put on the     *
  *                      queue.                                  *
  *                       - On checkpoint - IMS preserves the    *
  *                      UOWs of such messages in x'4040' log    *
  *                      records.                                *
  *                       - If IMS abends and is /ERE started -  *
  *                      these messages are retrived from the    *
  *                      logs                                    *
  *                      - If IMS abends and can not be /ERE     *
  *                      started - these messages are lost       *
  *                      - If the olds are re-used- some         *
  *                      messages are lost.                      *
  ****************************************************************
  * RECOMMENDATION: Install the APAR and use the functionality   *
  *                 after shared queue overflow and IMS cold     *
  *                 start after abend.                           *
  ****************************************************************
  Install the APAR.
  

Problem conclusion

Temporary fix

Comments

• Using CHKPT LAST with function RS (Recover for Shared Queues)
  
  1. Introduction
   New functionality is created for QCF IQCSELCT program
  with CHKPT LAST.... control statement.
   IQCSELCT allocates logs and extracts messages with
  unresolved UOWs .
   IMS writes x'67D0' log records for messages that can
  not be put on the shared queues.
   On checkpoint IMS preserves the UOWs for these
  messages in entries in x'4040' log records and -
  after the messages are put on the shared queues -
  entries in x'3F' log records.
   If there are messages with unresolved UOWs, and IMS
  abends and can be /ERE started, these messages are
  retrieved from the logs and put on the queues.
   If IMS abends and can not be /ERE started, but has
  to be COLD started - these messages are lost.
   If the online logs are re-used before a checkpoint
  is issued to recover these messages - these messages
  are lost.
   The new functionality is developed to extract messages
  from the logs, based on information in x'67D0', X'4040'
  and x'3F' log records.
  
  2. Function RECOVERAS
  The process is implemented in next steps:
  -SELECT step
  -SORT1 step
  -SORT2 step
  -CANCEL step
  -LOAD step
  
  2.1. SELECT step
  In SELECT step program IQCSELCT analyzes the execution parameter
  prepares LIST.LOG command for DBRC, reads
  the allocated logs and extracts several sets of
  records in output files.
  Control statement format with execution parameters:
  CHKPT LAST,imsid,RS,D=yyyy.ddd,T=hh:mm:ss,DT=CP
  FUNCTION RECOVERAS
  
  CHKPT LAST,imsid,RS,D=yyyy.ddd,T=hh:mm:ss,DT=MSG
  FUNCTION RECOVERAS
  
  CHKPT LAST,imsid,RS
  FUNCTION RECOVERAS
  
  
  Imsid      - is the 4 bytes IMSID
  RS         - recover after abend for shared queues
  D=..,T=... - is the date and time of the  restart
  checkpoint.
  (Selected checkpoint should be before the shared queues go in
  overflow condition)
  DT=CP
  After the parameters are checked, the logs data sets are
  allocated, starting with the log that has the start of the
  selected checkpoint.
  The logs are read and several output files are created:
  
  LOGOUT contains all selected input and output messages
  
  SCRAPSEL contains the not selected input and output messages
  (based on selection criteria and recoverability of the
  messages)
  
  CKPTOFIL contains formatted records created from x'67D0',
  X'4040' and x'3F' log records.
  
  2.2. SORT1 step
  In sort step SORT1 (see the sample job) CKPTOFIL is sorted
  by messages UOWs and by number of the log record.
  
  2.3. SORT2 step
  In sort step SORT2 (see sample job) LOGOUT is sorted by
  message's UOWs.
  2.4. CANCEL step
  In CANCEL step program IQCCAN1 reads sorted files and
  selects only messages with missing x'3F' records.
  Selected messages are put in the CANCLOUT file to be
  loaded in last LOAD step.
  
  CANCEL step ends with RC=0 if all UOWs with missing
  x'3F' records are found in the sorted file with
  logged messages.
  CANCEL step ends with RC=4 if some UOWs are not
  found in the sorted file with logged messages.
  In such case earlier restart checkpoint has to be used
  recovering the messages queues.
  
  3. JCL for Execution
  New sample - IQCRCAS - is added in hlqual.SIQCSAMP
  library.
  The sample JCL has to be customized. There are comments
  how to customize the JCL and parameters for allocation
  of all required data sets.
  ×**** PE13/11/20 FIX IN ERROR. SEE APAR PI06607  FOR DESCRIPTION
  

APAR Information

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

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

  UK97905

Modules/Macros

• H0GN310J IQC##### IQCACKPT IQCALST0 IQCASEGE
  IQCASELO IQCCANC1 IQCRCAS  IQCSELCT
  

Fix information

• Fixed component name

  IMS QUEUE CNTL

• Fixed component ID

  5697E9900

Applicable component levels

• R310 PSY UK97905

     UP13/09/26 P F309

Fix is available

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