PM46045: AFTER PM17542 SMF IO COUNTING AT THE DB2 ADDRESS SPACE LEVEL IS NO LONGER AVAILABLE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• After PM17542 SMF IO counting at the DB2 address space level is
  no longer available, which was not the intention.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 V10 users in z/OS 1.12 or higher.    *
  *                                                              *
  *                 All DB2 V8 and V9 users with PM17542         *
  *                 (UK60887, UK60888) applied in z/OS 1.12 or   *
  *                 higher.                                      *
  ****************************************************************
  * PROBLEM DESCRIPTION: With PM17542 applied, DB2 users may be  *
  *                      exposed to the z/OS problems:           *
  *                                                              *
  *                      - Overlay of high private storage with  *
  *                        a UCB address.  ABENDC78-54 when the  *
  *                        PPD eyecatcher for z/OS SIOTX cell    *
  *                        pool is overlaid with a UCB address.  *
  *                        SMCOVERLAY.                           *
  *                                                              *
  *                        Fixed by OA36101 (UA60221 UA60222).   *
  *                                                              *
  *                      - SMF record type 30 I/O counting info  *
  *                        at DBM1 address space level may have  *
  *                        missing counts.  SMF30TEP and         *
  *                        SMF30TEX contain invalid (lower)      *
  *                        values.                               *
  *                                                              *
  *                        Fixed by OA37361 and OA37362 (UA62296 *
  *                        UA62297)                              *
  *                                                              *
  *                      Note: PM17542 is in DB2 V10 base code.  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  PM17542 turns on SVC 99 parameter S99DASUP to suppress DD-level
  accounting when allocating a data set for a DB2 page set.  In
  this path, the storage overlay problem may occur.  The SMF
  record type 30 I/O counting at the DBM1 address space level is
  suppressed.
  

Problem conclusion

• The APARs and actions to be taken below are pertaining to DB2
  running in z/OS 1.12 or higher only.
  
  z/OS APAR OA36101 (allocation) must be installed as soon as
  possible to fix the potential storage overlay problem.
  
  z/OS APAR OA37361 (media manager) and OA37362 (VSAM) together
  will fix the missing address space level SMF I/O counting
  problem.  DB2 users should install them when available.
  
  From the DB2 side, PM46045 is used to provide an alternative for
  DB2 users to turn off S99DASUP.  The code is changed to tie
  S99DASUP to the setting of MEMDSENQMGMT when allocating a data
  set for a DB2 page set.  S99DASUP is set to on only when
  MEMDSENQMGMT is enabled.  So before the user could find a window
  to install z/OS fixes, PM46045 could be applied first.  By
  setting MEMDSENQMGMT DISABLE, the two z/OS problems can be
  avoided.
  
  Once all APARs (PM46045, OA36101, OA37361, OA37362) are
  installed, it is recommended to set MEMDSENQMGMT ENABLE to get
  the performance benefit.
  
  
  Instructions on setting MEMDSENQMGMT to DISABLE or ENABLE:
  ==========================================================
  Work with your system programmer to complete one of the
  following actions:
  
    - Update the ALLOCxx parmlib member to set the SYSTEM
      MEMDSENQMGMT value.
  
      SYSTEM MEMDSENQMGMT(DISABLE) or
      SYSTEM MEMDSENQMGMT(ENABLE)
  
    - Issue system command SETALLOC
  
      SETALLOC SYSTEM,MEMDSENQMGMT=DISABLE or
      SETALLOC SYSTEM,MEMDSENQMGMT=ENABLE
  
    Note:
    1.  Updating the ALLOCxx parmlib is strongly recommended as
        it remains effective across IPLs.
  
    2.  If SETALLOC SYSTEM,MEMDSENQMGMT command is used, a DB2
        restart is required to make the change effective.
  
    3.  System command D ALLOC,OPTIONS can be used to display the
        status of MEMDSENQMGMT in z/OS.
  
        Sample DISPLAY output:
  
        IEFA003I 15.35.15 ALLOC OPTIONS
        SPACE           PRIMARY:          4
                        SECONDARY:        24
        :
        SYSTEM          IEFBR14_DELMIGDS: LEGACY
                        TAPELIB_PREF:     EQUAL
                        REMIND_INTV:      90
                        VERIFY_UNCAT:     FAIL
                        TEMPDSFORMAT:     INCLUDELABEL
                        MEMDSENQMGMT:     ENABLE
  
  
  APARs interactions:
  ===================
  The following summarizes the interactions of DB2 APARs PM17542,
  PM46045, and z/OS APARs OA36101, OA37361, and OA37362.  It is
  intended to help you determine when to apply DB2 and z/OS APARs,
  and in what order.
  
  1.  PM17542 only - exposed to overlay and missing SMF I/O
      counting at address space level.  MEMDSENQMGMT irrelevent.
  
  2.  PM17542 with OA36101 - exposed to missing SMF I/O counting
      at address space level only.  MEMDSENQMGMT irrelevent.
  
  3.  PM17542 with OA36101, OA37361 & OA37362 - no longer exposed
      to either problem.
  
  4.  PM17542 with PM46045 - S99DASUP setting now only turned on
      when MEMDSENQMGMT is enabled.  Exposed to overlay and
      missing SMF I/O counting at address space level ONLY when
      MEMDSENQMGMT is ENABLED.
  
  5.  PM17542 with PM46045 & OA36101 - S99DASUP setting now only
      turned on when MEMDSENQMGMT is enabled.  Exposed to missing
      SMF I/O counting at address space level ONLY when
      MEMDSENQMGMT is ENABLED.
  
  6.  PM17542 with PM46045, OA36101, OA37361 & OA37362 - no longer
      exposed to either problem.  Performance benefits for both
      features introduced with PM17542 only available when
      MEMDSENQMGMT is ENABLED.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UK73300 UK73301 UK73302

Modules/Macros

• DSNB1OST
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK73300

     UP11/11/11 P F111 ®

• R810 PSY UK73301

     UP11/11/11 P F111 ®

• R910 PSY UK73302

     UP11/11/11 P F111 ®

Fix is available

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