DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

invoked; for example, the loading of the package into the EDM pool, or work that is done via
DBRMs in the plan that do not have a package.
The locking information at the package level is identical to the information you have in today’s
plan level accounting record.
Note: In V8, package-related accounting information is always stored in IFCID 239 and no
longer stored as part of IFCID 3 (plan level accounting).
Writing accounting records with KEEPDYNAMIC(YES)
If the DB2 DSNZPARM parameter CMTSTAT is set to INACTIVE (new default for DB2 V8),
DB2 writes an accounting record when a transaction commits and the connection qualifies to
become inactive. However, when using the KEEPDYNAMIC(YES) bind option, DB2 cannot
disconnect the connection from the thread (which happens when the connection becomes
inactive), because the thread contains information about locally cached statements.
Therefore DDF threads always have to remain active when using KEEPDYNAMIC(YES). As a
consequence accounting records are not cut at transaction boundaries. Likewise, DDF does
not reestablish WLM enclaves at transaction boundaries.
Although KEEPDYNAMIC(YES) still prevents DDF threads from becoming inactive in DB2
V8, using KEEPDYNAMIC(YES) still allows DB2 to cut accounting records at transaction
boundaries. When a new request arrives from the client system over the connection (that is
still active), a new enclave is created and a new accounting interval is started.
At commit time, when DB2 evaluates whether a DDF connection is eligible for inactivation, if
the only reason why it cannot become inactive is the presence of cached dynamic SQL
statements due to KEEPDYNAMIC(YES), DDF still cuts an accounting record, and also
completes the WLM enclave (as if KEEPDYNAMYIC(YES) were not specified). As in V7, the
presence of held cursors or declared temporary tables keeps the thread active and does not
allow accounting intervals or WLM enclaves to complete.
With this new behavior, you may now consider period-based WLM goals for threads that
commit frequently, but cannot become inactive only because they use KEEPDYNAMIC(YES).
Threads that cannot become inactive for other reasons do not reset the WLM enclave, and
period-based goals are probably not right for them (which was the case in the past).
4.12.5 SQLCODE -905 new IFCID 173
The current method of monitoring dynamic SQL statements that exceeded the resource limit
facility (RLF) ASUTIME time limit is inadequate. It does not provide the DBA with information
at the system level.
Description
Currently DB2 issues an SQLCODE -905 for the dynamic SQL statement which exceeds the
ASUTIME time limit set by the DBA. This is inadequate for the DBA to identify and act on it if
this is a recurring problem.
A new IFCID 173 trace record is written whenever a SQLCODE -905 is issued. For a
distributed system, IFCID 173 is issued at the site that the -905 error is issued except for a
statement that references a remote table with a three part name, then the IFCID 173 can be
issued at both the server and the requester.
This new IFCID 173 trace record is contained in trace type STAT CLASS(4) and PERFM
CLASS(3).
Chapter 4. DB2 subsystem performance 209