PH47626: DB2 13 FOR Z/OS SYSTEM PROFILE IMPROVEMENTS

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• Db2 13 for z/OS System Profile improvements
  
  Additional Symptoms and Keywords:
  db2spm spm profile_sys
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Distributed Data Facility (DDF) users.                   *
  * Specifically those that use profiles to                      *
  * monitor threads for remote clients that                      *
  * access Db2 using TCP/IP.                                     *
  * Db2 13 for z/OS (function level V13R1M500                    *
  * or higher).                                                  *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * System Profile monitor threads                               *
  * queuing improvements.                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When a MONITOR THREADS profile reaches its exception threshold
  limit, subsequent DBATs monitored by the same profile might be
  queued waiting for the next available DBAT slot, monitored by
  the same profile, to terminate or be pooled. When this event
  occurs, the current Db2 internal mechanism used to queue the
  DBAT incorrectly affects the system MAXDBAT value. The
  incorrect behavior might affect the overall performance of Db2
  in relation to the system-wide setting of the MAXDBAT
  subsystem parameter.
  Also, when the DBATs that are queued because of the profile
  exception condition, they are misrepresented as being Type1
  inactive DBATs being suspended
   Note: MAXTYPE1 subsystem parameter has been deprecated and
    it is no longer supported in Db2 13 or later.
  

Problem conclusion

Temporary fix

Comments

• Db2 for z/OS System Profile has been enhanced to provide
  additional thread status and DDF global system statistics
  counters related to DBATs that are queued when a profile
  exception was reached. This improvement will allow the user
  to clearly distinguish those DBATs that are in this waiting
  state when a profile exception occurs. Furthermore, this
  will eliminate the misunderstanding of those DBATs being
  queued (because of a profile exception) are not related to
  the deprecated MAXTYPE1 subsystem parameter.
  The changes introduced by PH47626 become available when
  function level V13R1M500 or higher is activated in Db2 13.
  Message DSNV402I from -DISPLAY THREAD command report:
  A new ST column value, 'RS', is implemented to uniquely
  identify a thread (DBAT) is being suspended because of a
  system profile exception condition.
  Example:
  DSNV402I  -DB2A ACTIVETHREADS
  NAME     ST A   REQ ID           AUTHID   PLAN     ASID TOKEN
  SERVER   RS *     2 abc          user1.   DISTSERV 1234     1
  The value of 'RS' is described as follows:
  RS - A DBAT is servicing a request from a remote client. The
       thread is suspended because a system profile MONITOR
       THREADS exception threshold was reached. The threshold
       is specified in the DSN_PROFILE_ATTRIBUTES ATTRIBUTE2
       column value for the associated profile PROFILEID row.
       The thread is queued until other threads that are
       monitored by the same profile deallocate or go inactive,
       providing an available slot. The thread resumes when a
       slot becomes available, and the thread is next in the
       queue.
  Existing value 'RQ' will be updated as follows:
  RQ - A DBAT is servicing a request from a remote client. The
       thread is suspended because the maximum number of
       active DBATs was reached, as specified by the MAXDBAT
       system parameter.
       DBATs are queued until other DBATs deallocate or go
       inactive, providing an available slot. The DBAT resumes
       when a slot becomes available, and the DBAT is next in
       the queue.
  Message DSNL093I from -DISPLAY DDF DETAIL command report:
  A new counter, PQDBAT, will be added to display the current
  number of DBATs queued because of a system profile exception
  threshold being reached.
  Example: When PQDBAT=0,  this means there are currently no
  DBATs queued because of a system profile exception.
  -DISPLAY DDF DETAIL
  ...
  DSNL093I DSCDBAT=0 INACONN=0 IUDBAT=0 PQDBAT=0
  Example: When PQDBAT=1,  this means there  is currently 1
  DBAT being queued because of a system profile exception
  threshold being reached.
  -DISPLAY DDF DETAIL
  ...
  DSNL093I DSCDBAT=0 INACONN=0 IUDBAT=2 PQDBAT=1
  The description of PQDBAT is as follows:
  PQDBAT - The current number of DBATs queued because a system
           profile exception threshold was reached. This value
           increases as more DBATs that match a system profile
           reach the specified exception threshold.
           This value decreases as DBATs that match the system
           profile terminate or the connection becomes
           inactive.
  The online product documentation for Db2 is updated for these
  changes:
  https://www.ibm.com/docs/en/db2-for-zos
  The global DDF system section of Db2 statistics which is
  mapped by DSNDQDST is being updated to include two new fields
  QDSTDBPQ and QDSTMDPQ.
  QDSTDBPQ - the current number of DBATs suspended due to
             system profile exception was reached.
  QDSTMDPQ - the maximum number of DBATs suspended due to
             system profile exception was reached since DDF
             started.
  A full description of the changes to DSNDQDST is provided in
  the ++HOLD DOC included with this APAR.
  The DSNWMSGS file, which contains full descriptions of all
  fields within a trace record for every IFCID, will be updated
  with changes made by this APAR in a documentation APAR at a
  later date.
  

APAR Information

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

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

  UI81803

Modules/Macros

• DSNLJEMG DSNFLDIR DSNVDTA  DSNDQDST DSNLTEXC DSNLTACT DSNWZDG2
  DSNWDFDS DSNLIRTR DSNFCDIR DSNLTDDF DSNWAKIS DSNLJTIN DSNWAACT
  DSNWVZPS DSNLTACC
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RD10 PSY UI81803

     UP22/08/12 P F208

Fix is available

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