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PI82517: TCPIP USAGE OF CSM STORAGE EFFICIENCY IMPROVEMENT

A fix is available

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APAR status

  • Closed as program error.

Error description

  • TCPIP caches storage for optimal reuse and optimizes the CPU
    overhead of obtaining and releasing storage by dividing larger
    blocks of storage into smaller areas.  This dividing process
    is optimal for CPU usage but can lead to a larger footprint of
    storage.  This caching and dividing effect extends to storage
    obtained from CSM which also divides larger blocks into smaller
    blocks for CPU efficiency.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users of the IBM Communications Server for z/OS Version  *
    * 2 Release 1 IP                                               *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * The TCP/IP usage of CSM can cause fragmentation in the CSM   *
    * buffers leading to CSM storage that is free but that cannot  *
    * be reused.                                                   *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Apply the PTF                                                *
    ****************************************************************
    When TCP/IP creates images of a CSM buffer, the CSM buffer
    cannot be reused until all the images have been released. The
    release of some of the images, but not all of the images, causes
    the storage represented by the released images to become
    unusable until all of the images are released.
    

Problem conclusion

  • The TCP/IP storage functions have been updated to recognize when
    CSM fragmentation is occurring and to release the CSM buffers
    causing the fragmentation.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI82517

  • Reported component name

    TCP/IP MVS

  • Reported component ID

    5655HAL00

  • Reported release

    210

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-06-02

  • Closed date

    2017-06-12

  • Last modified date

    2017-08-07

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

    PI80158

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

    UI47950 UI47951

Modules/Macros

  • EZBITSCU EZBIPINB EZBISXES EZBIFOUT EZBTLRDX EZBTCRD  EZBITSCS
    EZBSKDKI EZBITSMT EZBTCUTL EZATESEN EZATENCP EZBTLWRQ EZBIPOUT
    EZBTLCWK EZBISSHA EZATESDE EZBTCFRD EZBIFBP1
    

Fix information

  • Fixed component name

    TCP/IP MVS

  • Fixed component ID

    5655HAL00

Applicable component levels

  • R210 PSY UI47950

       UP17/07/28 P F707

  • R21K PSY UI47951

       UP17/07/28 P F707

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:
07 August 2017