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PH03468: MQ V9: S0C4 DISPATCHER PROCESS ERROR AFTER SEVERAL STOP CHANNEL COMMANDS

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Abend 0C4 did happen in chinit after running
    a script to stop channels via command to terminate client
    connections. Some of the commands were issued twice against the
    same IP address.
    .
    Additional keywords:
    ABEND0C4 ABENDS0C4 S00C4
    

Local fix

  • n.a.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
    *                 Release 0 Modification 0 and Release 1       *
    *                 Modification 0.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: Issuing multiple 'STOP CHL(x)           *
    *                      CONNAME(x.x.x.x) MODE(FORCE)' commands  *
    *                      to the same channel produces an 0C4     *
    *                      ABEND.                                  *
    ****************************************************************
    Issuing multiple 'STOP CHANNEL(x) CONNAME(x.x.x.x) MODE(FORCE)'
    commands to the same channel produces an 0C4 ABEND.
    
    The ABEND is caused due to an attempt to CANCEL the channel
    multiple times via asynchronous calls from the multiple 'STOP
    CHANNEL' commands.
    
    This opens up a timing window where the second time an attempt
    is made to CANCEL the channel some storage has already been
    freed by the first attempt and hence the 0C4 is produced.
    

Problem conclusion

  • Defensive code has been introduced to ensure that in the event
    that a call to CANCEL the same channel multiple times is made
    an 0C4 will not be produced. Additionally subsequent CANCEL
    channel calls to the same channel will not process the CANCEL.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PH03468

  • Reported component name

    IBM MQ Z/OS V9

  • Reported component ID

    5655MQ900

  • Reported release

    000

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-10-02

  • Closed date

    2018-11-26

  • Last modified date

    2019-01-02

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

    PI99255

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

    UI59902 UI59903

Modules/Macros

  • CSQXSCAN
    

Fix information

  • Fixed component name

    IBM MQ Z/OS V9

  • Fixed component ID

    5655MQ900

Applicable component levels

  • R000 PSY UI59902

       UP18/12/14 P F812

  • R100 PSY UI59903

       UP18/12/15 P F812

Fix is available

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Document Information

Modified date:
02 January 2019