PI39860: SIGNON COUNT VERY HIGH FOR CICS PLANS / PACKAGES SPECIFYING OPTHINT(' ')

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Customer noticed poor signon/transaction ratios after rebinding
  a plan. After the rebind, a ratio of 1:1 was occurring, which
  caused a performance degradation.  Application was a CICS
  transaction. It was determined that specifying OPTHINT('  ')
  (a string of blanks) was causing the signon to not be reusable.
  Additional Keywords/Symptoms:
  .
  If CICS RI component level 2 trace is active, you see a signon
  event traced for every transaction using the package/plan. Trace
  entries will look similar to the following:
  .
  AP 3260 D2D2  EVENT
  ABOUT_TO_ISSUE_DB2_SIGNON_WITH_PRIMARY_AUTH(XXXXX )
  AP 3261 D2D2  EVENT
  RETURN_FROM_DB2_SIGNON_WITH_PRIMARY_AUTH(XXXXX )
  .
  In the fully formatted AP 3260 trace entries, the data traced as
  parameter 4 is the DFHD2CSB control block. In a CICS 670 (4.2)
  release, the following two fields in this block are relevant:
  .
  CSB_THREAD_CREATED is x'04' bit at byte x'B4' in CSB.
  CSB_INITIAL_STATE is x'40' bit at byte x'B4' in CSB.
  .
  When this problem occurs, CSB_THREAD_CREATED bit is on, but
  CSB_INITIAL_STATE bit is off.
  
  Additional Note:
  If an existing CICS application exploits the defect that this
  APAR fixes, then the existing behavior of the application may
  change.
  

Local fix

• To get around this issue, remove the OPTHINT(' ') specification.
  This can be done by a BIND PLAN or BIND PACKAGE with the
  REPLACE and RETAIN keywords, and by not specifying the OPTHINT
  keyword.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: ALL DB2 10 and 11 for zOS users of the       *
  *                 OPTHINT bind option and the CURRENT          *
  *                 OPTIMIZATION HINT special register.          *
  ****************************************************************
  * PROBLEM DESCRIPTION: CICS threads are not being reused when  *
  *                      the CURRENT OPTIMIZATION HINT special   *
  *                      register is not explicitly set.         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The CURRENT OPTIMIZATION HINT special register was not
  checked to see if it was explicitly set when the
  determination was made for a thread to be reusable.
  A thread was marked non-reusable even when the special
  register was not explicitly set to a value different
  from the OPTHINT bind option.
  

Problem conclusion

• DB2 will check if the CURRENT OPTIMIZATION HINT special register
  is explicitly set to a value which is not the original before
  marking the thread non-reusable.
  
  Additional Keywords:  SQLSPECIALREG OPTHINT OPTHINTS
  

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:

  UI29633 UI29634

Modules/Macros

• DSNXECW  DSNXECWA DSNXECWU
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UI29633

     UP15/08/07 P F508

• RB10 PSY UI29634

     UP15/08/07 P F508

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.