Analyzing the reuse of threads

The IBM® OMEGAMON® for Db2 Performance Expert on z/OS® accounting report can help you identify, by plan, when threads were reused.

About this task

The following sections of the report contain information about the thread reuse:

  • NORMAL TERM.
  • ABNORMAL TERM.
  • IN DOUBT

Example

The following example reports shows the location of the following values:

  • NEW USER ( A ) tells how many threads were not terminated at the end of the previous transaction or query, and hence reused.
  • DEALLOCATION ( B ) tells how many threads were terminated at the end of the query or transaction.
  • APPL. PROGR. END ( C ) groups all the other reasons for accounting. Since the agent did not abend, these are considered normal terminations.
NORMAL TERM.      TOTAL  ABNORMAL TERM.      TOTAL  IN DOUBT            TOTAL
----------------  -----  ------------------  -----  -----------------   ------              
NEW USER  A           0  APPL.PROGR. ABEND       0  APPL.PGM. ABEND          0
DEALLOCATION  B       0  END OF MEMORY           0  END OF MEMORY            0
APPL.PROGR. END  C    0  RESOL.IN DOUBT          0  END OF TASK              0
RESIGNON   D          0  CANCEL FORCE            0  CANCEL FORCE             0
DBAT INACTIVE           0
TYPE2 INACTIVE        193
RRS COMMIT              0
END U. THRESH           0
BLOCK STORAGE           0
STALENESS               0

This technique is accurate in IMS but not in CICS®, where threads are reused frequently by the same user. For CICS, also consider looking at the number of commits and aborts per thread. For CICS:

  • NEW USER ( A ) is thread reuse with a different authorization ID or transaction code.
  • RESIGN-ON ( D ) is thread reuse with the same authorization ID.