PK69339: AUTOMATIC KEEPDYNAMIC DISTRIBUTED THREAD REFRESH

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• DB2DDF DDFL09 DB2INACTIVE feature pk69339 fpk69339
  Automatic refresh of distributed thread (DBAT) which uses
  packages bound with keepdynamic(yes)
  *******************************************************
  Additional symptoms and keywords:
    DBAT KEEPDYNAMIC REFRESH
    Short on Storage SOS
    KeepDynamic Keep Dynamic
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Distributed Data Facility (DDF) users.   *
  *                 Specifically where DB2 is being accessed     *
  *                 by distributed applications using the IBM    *
  *                 Data Server Driver or Client product family  *
  *                 and the packages utilized by the application *
  *                 were bound with KEEPDYNAMIC(YES).            *
  ****************************************************************
  * PROBLEM DESCRIPTION: Task abends occur due to storage        *
  *                      getmain calls failing which were        *
  *                      caused by the fragmentation of the      *
  *                      virtual storage within the              *
  *                      ssidDBM1 address space.                 *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When distributed client applications utilize packages
  that have been bound with KEEPDYNAMIC(YES), the distributed
  threads (DBATs) remain active with the connection.  The reason
  for the thread remaining active is a local prepared statement
  cache is created for the application session so that the
  application only needs to execute a statement once it has been
  prepared, regardless of whether or not a commit has been
  performed.  Without KEEPDYNAMIC(YES) on the packages, the
  application would have to always reprepare a statement prior
  to executing the statement if a commit had been performed
  since the last time the statement was prepared.  The thread
  can then potentially remain active with the connection for
  an extended period of time.  As the thread accumulates new
  prepared statements over time, the thread's storage footprint
  in the ssidDBM1 address space will grow.  Also, over time, as
  the storage is acquired and possibly released by the thread
  due to different application statements being processed, the
  virtual storage within the ssidDBM1 address space could be
  fragmented in such a way that requests for storage within
  the address space for this and other threads will fail.
  These storage failures will result in task abends and
  application outages.
  

Problem conclusion

Temporary fix

Comments

• DDF has been changed to support a concept called KeepDynamic
  DBAT refresh.  This support requires that the DDF THREADS
  (DSN6FAC CMTSTAT) subsystem parameter be set to INACTIVE.
  Also, this support can only be activated for a DBAT which is
  serving a connection from an application using the IBM Data
  Server Driver or Client for JAVA.  The driver/client must
  connect directly to DB2 9 for z/OS and the driver/client must
  have support for Sysplex Workload Balancing and/or Seamless
  Failover.  The DataSource used by the application must have
  the "enableSysplexWLB" property set to true or the
  "enableSeamlessFailover" set to true.  Since the application
  is utilizing KeepDynamic capabilities, the DataSource must
  also have the required KeepDynamic properties set.
  When DDF receives a connection request from such an appli-
  cation session, DDF will now be able to terminate the
  the DBAT/connection after it has been used for over one hour
  or it has remained idle for over 20 minutes.  This connection
  outage will then cause the client/driver to redrive a new
  connection against the same server or a possibly different
  member of the serving data sharing group.
  The application should be able proceed as if nothing happened
  to its connection.  By terminating the DBAT/connection, DDF
  will have temporarily alleviated the virtual storage demand
  within the ssidDBM1 address space, allowing the DB2 subsystem
  to continue operations unabated.
  ž**** PE09/12/01 FIX IN ERROR. SEE APAR PM02383  FOR DESCRIPTION
  

APAR Information

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

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

  UK50565

Modules/Macros

• DSNDDPSB DSNLAGNX DSNLBABR DSNLEDDA DSNLQACT
  DSNLQCTL DSNLQDIS DSNLTEXC
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• R910 PSY UK50565

     UP09/10/13 P F910

Fix is available

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