PM41119: ABEND04E RC00E2000B DSNXERT2 DSNSVBK +062A STORAGE SHORTAGE / LEAK

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• ABEND04E RC00E2000B DSNXERT2 DSNSVBK +062A storage shortage /
  leak . Major storage consumer is DSNXERT2 allocating SQLDA
  blocks . Abend symptoms occurred at the intermediate site in
  implicit DRDA hop scenario .
  .
  Additional symptoms:
  ABEND04E RC00E20003 DSNXERT2 DSNSVBK +05EE  +05EA
  ABEND04E RC00E20016 DSNSVSTK+0656
  MSGDSNV508I  SQLSTORAGE  DB2STGLK/K
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: DB2 9 for z/OS users of static 3-part name   *
  *                 SELECT INTO and DBPROTOCOL(DRDA)             *
  *                 (known as implicit DRDA) in a DRDA HOP       *
  *                 scenario                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: ABEND04E RC00E2000B                     *
  *                      DSNXERT2 DSNSVBK +062A                  *
  *                                                              *
  *                      or                                      *
  *                                                              *
  *                      significant CPU performance degradation *
  *                      for DSNSVBK occurred while running      *
  *                      an application that used                *
  *                      a static implicit DRDA SELECT INTO in   *
  *                      a multi-site DRDA HOP scenario          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  
  ABEND04E RC00E20004 in DSNSVBK  occurred in a long running
  DB2 thread that ran an extended workload of applications that
  contained static SELECT INTO statements using implicit DRDA
  (SQL bound with DBPROTOCOL(DRDA) and referencing 3-part object
  names) in a multi-site HOP scenario.
  Reason code 00E20004 indicates that DB2 has exhausted its
  available memory storage ( out of storage condition ).
                                                                 .
  The SELECT INTO is also known as a singleton SELECT (as compared
  to a cursor SELECT), and static implicit DRDA SQL statements
  have value 'D' in DB2 catalog column SYSIBM.SYSPACKSTMT.STATUS .
                                                                 .
  A HOP site scenario can involve DRDA CONNECT SQL (and/or
  a remote stored procedure ), implicit DRDA SQL and multiple DB2
  sites as follows:
     Requester_site1 -> DB2_site2 -> DB2_site3 (or back to site1)
  where
    "->" means explicit or implicit DRDA connect,
    Requester_site1 can be DB2 z/OS or non-z/OS client,
    DB2_site2 is known  as the " intermediate " site, and
    DB2_site3 is known as the " downstream " server.
  
  The AB04E RC00E20004 occurred at the intermediate site
  (DB2_site2).
                                                                 .
  When we examined a storage map of the intermediate DB2's ADMF
  Agent Local ( AGL ) storage pool in the dump provided, we saw
  an excessive number of DB2 internal blocks with eyecatcher SQLDA
  that were allocated by DB2 csect DSNXERT2.  This particular
  internal SQLDA block is allocated by DB2 specifically to process
  static SELECT INTO statements at the intermediate DB2 in a HOP
  scenario. After further review, we determined that a storage
  leak for this SQLDA block occurred.
  
  This excessive number of SQLDA blocks can also cause
  a noticeable CPU performance degradation focused in DB2 csect
  DSNSVBK due to the increasingly growing chain of SQLDA blocks
  that DSNSVBK had to follow each time an allocation of a new
  SQLDA block was needed for a static SELECT INTO case.
  

Problem conclusion

• DB2 code has been corrrected to free this internal SQLDA block
  after its use at the intermediate DB2 when processing static
  implicit DRDA SELECT INTO statements.
                                                                 .
  This also improves CPU performance for DB2 csect DSNSVBK.
                                                                 .
  The PTF for this apar must be applied at the intermediate DB2
  (DB2_site2) of a HOP site scenario where the 'out of storage'
  AB04E in DSNSVBK occurred or where the CPU performance
  degradation for DSNSVBK is observed.
                                                                 .
  Additional search keywords: SQLPERFORMANCE PERF DBPROTOCOL DDF
  

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:

  UK69691

Modules/Macros

• DSNXERT2
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• R910 PSY UK69691

     UP11/07/29 P F107

Fix is available

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