PM79711: BMP REGION GOT ABENDU1033 WHEN MANY DEDB FLD CALLS WERE MADE

A fix is available

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APAR status

  • Closed as program error.

Error description

  • After application of PM60126, some BMP region got ABENDU1033.
    These BMPs issued many DEDB FLD calls and issued SYNC call when
    they got statusFW. During SYNC process, FLD calls were
    reprocessed and needed additional buffers. Finally, buffer usage
    exceeded NBA + OBA and ABENDU1033 happened.
    Originally, IMS needed to reserve the buffers which are used
    to reprocess FLD calls during SYNC. But the fix in PM60126 made
    these buffers available to be reused for other purpose.
    When IMS returned statusFW, other DL/I calls stealled these
    buffers already, and enough buffers were not available already.
    --------------------------------------------------
    Sample Case-1;  BMP ABENDU1033.   NBA=4 and OBA=1
      1. FLD call;  DMHR1 was used to read CI-A
                    DMHR2 was used to save DFLD logics.
      2. FLD call;  DMHR3 was used to read CI-B
                    DMHR2 was used to save DFLD logics.
      3. GHU call;  DMHR4 was used to read CI-C
      4. REPL call; DMHRNALT was updated in DMHR4.
      5. GHU call;  DMHR3 was stolen to read CI-D
      6. REPL call; DMHRNALT was updated in DMHR3.
      7. FLD call;  DMHR1 was stolen to read CI-E
                    DMHR2 was used to save DFLD logics.
      8. SYNC call;  ( DMHR2, DMHR3 and DMHR4 are not stealable. )
           DBFSFLD0 reprocessed FLD calls using DFLDs.
              DMHR1 was used to read CI-A
              DMHR5 was obtained from OBA !!! to read CI-B
              additional buffer was requested to read CI-E, but no
              OBA buffer remained.
              BUSE = NBA+OBA already and DBFCBHL0 returned RC=12
          <-------
        ABENDU1033
    ----------------------------------------------------------------
    During analysis of this problem, we found another problem at
    prior level than PM60126. Timing of statusFW was wrong.
    StatusFW tells application program to the recommended timing of
    SYNC call. Our expectation is when all NBA buffers were used and
    prior to get OBA buffers.
    But when statusFW was returned to BMP, OBA buffers were used and
    OBA lock was held unexpectedly. This is because
    IMS is missing to consider the fact that these buffers with
    DMHRFFPR flag on cannot be stolen.
    ----------------------------------------------------------------
    Sample Case-2;  Prior to PM60126, statusFW       NBA=4 and OBA=1
      1. FLD call;  DMHR1 was used to read CI-A  :DMHR1 has DMHRFFPR
                    DMHR2 was used to save DFLD logics.
      2. FLD call;  DMHR3 was used to read CI-B  :DMHR3 has DMHRFFPR
                    DMHR2 was used to save DFLD logics.
      3. GHU call;  DMHR4 was used to read CI-C
      4. REPL call; DMHRNALT was updated in DMHR4.
      5. GHU call;  DMHR5 was obtained from OBA to read CI-D
                                             <== OBA lock held
          <------ StatusFW
      6. SYNC call;
           DBFSFLD0 reprocess FLD calls using DFLDs.
              DMHR1 used to read CI-A
              DMHR3 used to read CI-B
    ----------------------------------------------------------------
    StatusFW should be returned at above REPL call.
    

Local fix

  • Increase OBA to bypass ABENDU1033.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: IMSFP V11 users with FLD calls.              *
    ****************************************************************
    * PROBLEM DESCRIPTION: BMP regions get ABENDU1033 when         *
    *                      several FLD calls are issued.           *
    ****************************************************************
    * RECOMMENDATION: INSTALL CORRECTIVE SERVICE FOR APAR/PTF      *
    ****************************************************************
    BMPs issued many DEDB FLD calls and issued SYNC when they
    got statusFW. During SYNC process, FLD calls were reprocessed
    and they needed additional buffers. Finally the buffer usage
    exceeded NBA + OBA and the ABENDU1033 occurred.
    Previous service had made these buffers available to be reused
    for other DL/I calls so when statusFW was issued and needed
    more buffers, they had already been exhausted. Hence, the
    ABENDU1033.
    
    Also, the timing of statusFW is incorrect. StatusFW advises
    the application to time SYNC calls appropriately. The
    expectation is the application would get the STATUS FW when NBA
    buffers are all used and prior to using OBA buffers.
    But when the statusFW was returned to the BMP the OBA buffers
    were used and the OBA lock was held unexpectedly.
    

Problem conclusion

  • GEN:
    KEYWORDS:
    
    *** END IMS KEYWORDS ***
    
    **********
    DBFIRC10 *
    **********
    Code added to check if Procopt=GO buffers exist and can be
    stolen in addition to the DMHRFFPR (prevent buffer steal) flag
    set off before made available to the region.
    
    **********
    DBFMFL00 *
    **********
    Code changed to turn DMHRFFPR ON to reserve this DMHR until
    SYNC. DBFSFLD0 needs this DMHR to reprocess the FLD call.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM79711

  • Reported component name

    IMS V11

  • Reported component ID

    5635A0200

  • Reported release

    100

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-12-24

  • Closed date

    2013-05-10

  • Last modified date

    2013-06-04

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

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

    PM88254 PM88255 UK94212

Modules/Macros

  •    DBFIRC10 DBFMFL00
    

Fix information

  • Fixed component name

    IMS V11

  • Fixed component ID

    5635A0200

Applicable component levels

  • R100 PSY UK94212

       UP13/05/14 P F305

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.



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Document information


More support for:

IMS

Software version:

100

Reference #:

PM79711

Modified date:

2013-06-04

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