PH08814: MESSAGE QUEUES CAN BUILD AFTER 100 MESSAGES ARE IWAITED/STOPPED WITH SUBSEQUENT MESSAGES BEING RELEASED, RISKING AN IMS ABEND

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• After 100 messages are iwaited (or stopped) the next messages
  are released which could cause queue build-up and an IMS abend.
  As part of this fix we'll:
   1) Remove the restriction to get up to 100 action list cells.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All IBM IMS Queue Control Facility for z/OS  *
  *                 Version 3 Release 2 (FMID=H0GN320) users     *
  *                 in a nonshared queue environment.            *
  ****************************************************************
  * PROBLEM DESCRIPTION: After about 100 messages are iwaited    *
  *                      (or stopped) the next messages are      *
  *                      released which could cause queue        *
  *                      build-up and an IMS abend.              *
  ****************************************************************
  * RECOMMENDATION: Apply the maintenance for this APAR.         *
  ****************************************************************
  The total number of taking all ACTION(STOP, ABEND, WAIT, WTO) in
  all FAILSAFE and AREA ranges is about 100 times. If it exceeds
  100 times, QCF Queue Space Overflow Protection does not work.
  QCF does an ACTION using an entry in the QSUN cell pool built
  in the IMS control region. The cell pool has 100 entries, even
  if all 100 entries are used up, QCF does not expand the cell
  pool. The messages are bypassed QCF Queue Space Overflow
  Protection, released to IMS, and inserted in the message queue.
  It must recycle IMS to get QCF Queue Space Overflow
  Protection working again, but there is no way to know if it has
  exceeded 100 times. This design does not reduce the risk of an
  IMS ABEND due to queue overflow.
  

Problem conclusion

• To expand QSUN cell pool, QCF provides a new
  ACTIONPOOL(MAXPOOL=nnn) statement in the IMS Queue Control
  Facility extensions PROCLIB member.
  To notify cell pool usage, IMS Queue Control Facility issues new
  IQC6821I and IQC6822W messages in the IMS control region job log
  or dependent region job log.
  IQC6821I is issued each a cell pool is used up, IQC6822W is
  issued when all cell pools are used up.
  The user can take the action on many messages and plan to
  recycle IMS as needed.
  
  In addition, QCF has been changed as follows:
  - For ACTION=STOP, QCF return always the status code A7 (or a
    related message) against the same source that continues to
    send new messages without stopping after receiving the status
    code A7 once.
  - It can release more than 100 messages at once using "- Release
    all displayed tasks" in "Table Actions" menu on QCF ISPF UI
    "4 Wait".
  
  ========================
  = Documentation Change =
  ========================
  IBM IMS Queue Control Facility for z/OS Version 3 Release 2,
  User's Guide and Reference (SC19-4005-05) should be changed as
  follows:
  ================================================================
  > Configuring IMS Queue Control Facility
  >> Server and extension reference
  >>> Extensions PROCLIB member reference
  * The following statement is added before AREA statement.
  ----------------------------------------------------------------
  ACTIONPOOL
  
  >>--ACTIONPOOL--(--+----------------------+--)--<<
                     |                      |
                     |            +----1-+  |
                     |            |      |  |
                     +--MAXPOOL=--+------+--+
                                  |      |
                                  +--nnn-+
  MAXPOOL=nnn
       The MAXPOOL parameter specifies the maximum number of QSUN
       cell pools.
       The valid range is 1 to 100.
       The default is 1.
       One cell pool can take QSUN processing (ACTION=WAIT,
       ACTION=STOP, ACTION=WTO, etc.) about 100 times.
       If all cell pools are used up, the messages are passed to
       IMS without QSUN processing.
       To activate QSUN processing again, IMS must be recycled.
  ----------------------------------------------------------------
  
  ================================================================
  > Troubleshooting
  >> Runtime messages (IQC)
  >>> IQC6628E
  * Add the following page.
  ----------------------------------------------------------------
  IQC6628E NUMERIC VALUE OUTSIDE OF ALLOWABLE RANGE FOR MAXPOOL
  Explanation
    The number that was specified in the MAXPOOL parameter is
    outside of the range for that value.
  System action
    Processing terminates.
  User response
    Correct the MAXPOOL=value and run the job.
  Module
    IQCSIN10,IQCCIN00
  ----------------------------------------------------------------
  
  ================================================================
  > Troubleshooting
  >> Runtime messages (IQC)
  >>> IQC6821I
  * Add the following page.
  ----------------------------------------------------------------
  IQC6821I QSUN ACTION ENTRIES HAVE USED UP  mmm POOLS OUT OF THE
  MAX nnn POOLS
  
  Explanation
    The mmm value is the number of used up cell pools.
    The nnn value is the total number of the cell pools.
  System action
    Processing continues.
  User response
    None. This message is for informational purposes only.
  Module
    IQCCQAT0
  ----------------------------------------------------------------
  
  ================================================================
  > Troubleshooting
  >> Runtime messages (IQC)
  >>> IQC6822W
  * Add the following page.
  ----------------------------------------------------------------
  IQC6822W QSUN ACTION ENTRIES HAVE USED UP ALL nnn POOLS
  
  Explanation
    The nnn value is the number of used up cell pools.
    This message indicates that subsequent messages from all
    sources may be inserted to the message queue without QSUN
    processing.
  System action
    Processing continues.
  User response
    To activate QSUN processing again, recycle IMS.
  Module
    IQCCQAT0
  ----------------------------------------------------------------
  

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:

  UI67650

Modules/Macros

• IQCC00   IQCC1ENU IQCCIN0E IQCCIN0F IQCCQATE IQCCQATF IQCQMR1E
  IQCQMR1F IQCSIN10
  

Fix information

• Fixed component name

  IMS QUEUE CNTL

• Fixed component ID

  5697E9900

Applicable component levels

• R320 PSY UI67650

     UP20/02/04 P F002

Fix is available

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