PM80880: PERSISTENT JVM IN MPP PERFORMANCE ENHANCEMENT: DB2 JCC CONNECTION RE-USE.

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• Provide function to allow DB2 JCC connection re-use for better
  performance in an IMS  Persistent JVM MPP environment.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All IMS V12 users of Persistent JVM in       *
  *                 MPP/BMP/IFP where the IMS MPP/BMP/IFP        *
  *                 application invokes a Java application which *
  *                 makes DB2 calls through DB2 JCC              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Performance issue due to the DB2 JCC    *
  *                      connection not being re-used if the     *
  *                      security environment has not been       *
  *                      changed (ie.  transaction origin userid *
  *                      has not changed)                        *
  ****************************************************************
  * RECOMMENDATION: INSTALL CORRECTIVE SERVICE FOR APAR/PTF      *
  ****************************************************************
  For an IMS MPP/BMP/IFP application executing in a Persistent JVM
  environment and calling a Java application which makes DB2 calls
  through DB2 JCC, there exists a potential negative performance
  impact due to the DB2 JCC connection not being re-used if it can
  be re-used.  Basically, the DB2 JCC connection can be re-used if
  the transaction origin userid has not changed between
  transaction boundaries.
  
  IMS controls the DB2 JCC connection during IMS syncpoint
  processing by invoking the DB2 JCC method ExternalOps.reset() to
  tell DB2 JCC to reset the connection in preparation for the next
  transaction.
  
  To resolve this issue, IMS will leverage a DB2 JCC function
  which allows the DB2 JCC connection to be re-used if the
  transaction userid has not been changed between transactions.
  
  This service has the following software dependency:
  
  - If you specify DB2JCC_CONN_REUSE=Y (defined below), DB2 APAR
    PM77184 (JCC3.64) or DB2 APAR PM77185 (JCC4.14) is required.
  

Problem conclusion

Temporary fix

Comments

• With this maintenance, IMS introduces user option
  DB2JCC_CONN_REUSE=Y|N which is specified in the ENVIRON= member
  of the dependent region (eg.  member DFSJVMEV)
  
  PARMBLK:
  Added new field PCDB2JCR to contain DB2JCC_CONN_REUSE= value.
  
  DFSPCC20:
  Added logic to pass address of field PCDB2JCR to DFSJVM00 during
  JVM creation so DFSJVM00 can properly set field PCDB2JCR with
  the DB2JCC_CONN_REUSE= value.
  
  DFSJVM00:
  Added logic to recognize the new DB2JCC_CONN_REUSE option and
  set new field PCDB2JCR accordingly.
  
  DBFFPPR0:
  DFSTMPR0:
  Added supporting code for new DB2JCC_CONN_REUSE function which
  examines new field PCDB2JCR to determine whether or not to
  invoke DB2 JCC in a way that the DB2 JCC connection can be
  re-used for the subsequent transaction.
  
  DBFHGU10:
  DFSCPY00:
  Added supporting code for new DB2JCC_CONN_REUSE function.
  
  DFSPCJB0:
  DFSPCJM0:
  Recompiled due to JVMFSPLL length change and some field
  offset changes to JVMFSPL  DSECT.
  
  
  ***************** PUBS CHANGES *******************************
  
  Book: GC19302101 - System Definition
  
  In section "Parameter descriptions for IMS procedures", under
  the ENVIRON= parameter description, add the following
  description for the new DB2JCC_CONN_REUSE parameter that can be
  specified in the ENVIRON= member:
  
  DB2JCC_CONN_REUSE= Y | N
      Specifies whether (Y) or not (N) you want IMS to communicate
      to DB2 JCC that the DB2 JCC connection should be re-used if
      possible for the next transaction. The default is N.
  
      This option is recognized only for MPP, BMP, and IFP
      regions.
  
      Note: If DB2JCC_CONN_REUSE=Y is specified, the DB2 JCC
      connection will only be re-used if the transaction userid
      for the next transaction is the same as the userid for the
      previous transaction.
  
  
  Book: GC18971408 - Messages and Codes, Volume 3: IMS Abend Codes
  
  Under the U0101 description, under section "For DFSPCC20:", add
  the following for V12 and above only:
  
   "Reg7 and Reg8 together contain the value of field RCPGM
    (program name) at time of abend."
  
  Under the U0101 description, under section "For DFSPCC20:", add
  the following to the description of reason code 5 only
  (Reg15=X'5') and for V12 and above only:
  
  "If Reg3=X'0C', message DFS650E precedes this abend."
  
  
  Book: GC18971208 - Messages and Codes, Volume 1: DFS Messages
  
  DFS650E
  
  NON-LE COMPLIANT PROGRAM IN PERSISTENT JVM ENVIRONMENT,
  NAME=program name
  
  Explanation
  
  The user attempted to load and execute a non-Language
  Environment (LE) compliant/conforming program in a persistent
  JVM dependent region environment.  Any program that executes in
  a persistent JVM dependent region environment must be LE
  compliant/conforming.
  
  System action
  
  ABENDU0101-05 (reason code 5) is issued to terminate the
  application.
  
  Programmer response
  
  Correct the program to make it LE compliant/conforming.  The
  program did not contain a valid LE entry prolog.  Make sure that
  the program was compiled with a current LE enabled compiler.
  See z/OS Language Environment Programming Guide (SA22-7561) for
  a description of LE compliant/conforming programs.
  
  Module
  
  DFSPCC20
  
  
  Book: GC19301902 - Release Planning Guide
  
  In a mixed Java/COBOL environment, APAR PM80880 provides the
  ability to re-use DB2 JCC connections for MPP, BMP, and IFP
  region programs that invoke a Java application which accesses
  DB2 through DB2 JCC.
  
  The DB2JCC_CONN_REUSE=Y|N parameter is now supported in the
  PROCLIB member that is specified on the ENVIRON= parameter.  The
  default is N.
  
  If DB2JCC_CONN_REUSE=Y is specified, the DB2 JCC connection will
  only be re-used if the transaction userid for the next
  transaction is the same as the userid for the previous
  transaction.
  

APAR Information

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

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

  PM81408 UK91884

Modules/Macros

• DBFFPPR0
  DBFHGU10
  DFSCPY00
  DFSJVM00
  DFSPCC20
  DFSPCJB0
  DFSPCJM0
  DFSTMPR0
  PARMBLK
  

Fix information

• Fixed component name

  IMS V12

• Fixed component ID

  5635A0300

Applicable component levels

• R200 PSY UK91884

     UP13/02/22 P F302  

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.