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PM97943: ABEND4C5 RC74FF2500 ECSA STORAGE SHORTAGE DUE TO DUSA EXPANSIONS

A fix is available

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APAR status

  • Closed as program error.

Error description

  • A large number of TCP connections are terminated simultaneously
    resulting in large number of finwait2 timers scheduled in the
    same time slot.  When the timer expires, the termination
    processing of each connection results in an expansion of the
    dynamic savearea (DUSA).  Each DUSA expansion results in
    the use of an additional 36k ( x'9000' ) area of storage.
    The spike in ECSA, subpool 241 key 6, storage can cause
    ECSA to be depleted.
    

Local fix

  • If the TCPIP stack leaves the sysplex, once ECSA storage use
    by TCPIP is no longer an issue, the VARY command
      VARY TCPIP,,SYSPLEX,JOINGROUP
    can be issued to allow the TCPIP stack to rejoin the sysplex.
    TCPIP's ECSA storage use can be monitored with the command
       DISPLAY TCPIP,,STOR
    ADDITIONAL SYMPTOMS:
    -  If SYSPLEXMONITOR is enabled, the storage shortage could
       cause the stack to leave the sysplex.  This would be
       accompanied by EZD1973E MULTIPLE TCPIP NONRECOVERABLE ERRORS
       ARE ADVERSELY AFFECTING SYSPLEX PROCESSING and EZZ9676E
       SYSPLEX PROBLEM DETECTION CLEANUP HAS SUCCEEDED FOR TCPIP
       messages.
    .
    KEYWORDS:  AB4C5 4C5 2500 RC2500 SP241 K6 241 6 DUCB DUSA 9000
    FINWAIT2
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users of the IBM Communication Server                    *
    * for z/OS Version 2 Release 1 IP:                             *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * ABEND4C5 RC74FF2500 ECSA storage                             *
    * shortage during simultaneous                                 *
    * termination of TCP connections.                              *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Apply fix.                                                   *
    ****************************************************************
    The problem can be summarized as follows:
    1. A server was terminated resulting in a FIN request sent
    to each connection partner client.
    2. The client ACKed the FIN, but did not return a FIN.
    3. The TCP server host started a FINWAIT2 timer.
    4. All FINWAIT2 timers expired simultaneously and proceeded
    with connection cleanup.
    5. Each process executing connection termination obtained
    DUCB/DUSA control blocks from ECSA storage. The amount
    storage obtained caused a temporary storage spike in
    ECSA usage and exceeded available ECSA.
    

Problem conclusion

  • TCPIP has been modified to not process all FINWAIT2
    timer expirations simultaneously, and therefore
    avoid a storage spike.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM97943

  • Reported component name

    TCP/IP V3 MVS

  • Reported component ID

    5655HAL00

  • Reported release

    210

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-09-26

  • Closed date

    2014-01-16

  • Last modified date

    2014-04-02

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

    PM93018

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

    UI14307

Modules/Macros

  • EZBTCRD
    

Fix information

  • Fixed component name

    TCP/IP V3 MVS

  • Fixed component ID

    5655HAL00

Applicable component levels

  • R210 PSY UI14307

       UP14/03/13 P F403

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

Modified date:
02 April 2014