PI78979: REAL STORAGE USAGE STATISTICS CONTAINED IN IFCID225 IFCID0225

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• REAL STORAGE usage statistics.                           (44080)
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All DB2 z/OS V12 users. Requires z/OS                        *
  * apar OA50366 be installed and IFCID 503                      *
  * enabled before non-zero values are                           *
  * returned for the new IFCID0225 record                        *
  * fields. OA50366 may be installed                             *
  * before or after PI78979.                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * IFCID225 Real Storage statistics                             *
  * record shows the total number of                             *
  * Real Frames charged to DB2, but                              *
  * many of these frames may have been                           *
  * discarded and are available for steal.                       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  The IFCID0225 storage statistics record contains field values
  for the number of Real Storage pages charged to DB2 for 31 and
  64-bit virtual.  These values are the current high water values
  and would only be the actual frames in use if the system were
  actively paging and stealing all of the discarded frames, or
  the frames have been stolen to replenish the frame available
  queues.  Systems that have large amounts of REAL MAIN
  MEMORY and never page would likely always display the high
  water value. When DB2 ZPARM RealStorage_Management is ON
  or AUTO, contracted pages or pages freed during thread
  termination, are DISCARDDATA KEEPREAL(YES) and remain backed
  and charged against DB2 until or unless they are stolen.
  

Problem conclusion

• The IFCID0225 record will now contain a new bit flag,
  QW0225DPGS, indicating this record contains return
  values for the following new fields:
  - QW0225ShrStkstg_dpage
  - QW0225PriStg_dpage
  - QW0225ShrStg_dpage
  - QW0225ComStg_dpage
  These fields will be zero in all records if QW0225DPGS is OFF,
  or if macro call result return count is zero, or if OA50366 is
  not applied.  The IARV64 COUNTPAGES option, which contains the
  new DISCARDPAGES(YES) keyword, will be issued only once each
  day at approximately midnight local time, if new IFCID503 is
  active. At the time this function is performed, an increase in
  DB2 MSTR TCB time will be observed.  This increase may be
  many times the normal observed and is dependent on the amount
  of 64-bit storage in-use by this member. The collection occurs
  only once per day due to the cost of the serialization and
  instructions to return these values for each non-bufferpool
  object. If RealStorage_management = OFF, or IFCID0503 is OFF,
  this request will not be issued since there would be no
  discarded frames or user does not want the data. The above
  new fields represent the count of DISCARDED frames which
  have not been stolen or re-referenced since the DISCARD was
  performed. The actual Real Frames in use at this interval,
  may be calculated by the following where xxx = any one of
  the four different new count fields above:
  
  QW0225xxxStg_Real + QW0225xxxStg_Aux - QW0225xxxStg_dpage
  

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:

  PI82191 UI49138

Modules/Macros

• DSNVMON  DSNTXSTB DSNWVZXT DSNWDFSM DSNDQW03 DSNLTMSC DSNYASCP
  DSNDQWHS DSNWVINT
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI49138

     UP17/08/11 P F708

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.