PI82517: TCPIP USAGE OF CSM STORAGE EFFICIENCY IMPROVEMENT

Obtain the fix for this APAR.

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 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.