Basis Errors and Solutions

Symptom

The SAP DB2 performance data collector RFCOSCOL (WebAS 6.20/6.40) / SAPCL (WebAS 7.00) periodically takes a snapshot of the DB2 statement cache statistics in order to collect a history of the performance data. CPU spikes may occur on the z/OS machine while the performance data is being collected.
Other terms

DB2,z/OS,IFCID 316, ST04
Reason and Prerequisites

RFCOSCOL (Release 6.20/6.40) and the SAPCL alert router (Release 7.00) collect a history of the statement cache statistics with a frequency that is always controlled by DB2 ZPARM STATIME.
Solution

New configuration options for the collection of the statement cache history have been introduced. In SAP transaction ST04 on the ‘SAP Collector Settings’ panel of the ‘Checks/Settings’ tab now includes the following parameters:
History interval: By default, the most relevant statements in the statement cache are determined with a frequency controlled by the DB2 ZPARM STATIME. You can modify this frequency by specifying a multiplier. For example, if STATIME is set to 5 minutes and the multiplier is 3, then the most important statements will be determined and stored every 15 minutes. If you specify 0, you turn off the collection of the statement cache history.Keep top N statements: By default, the top 50 statements with the largest elapsed time in the last history interval are stored in the statement cache history. You can change this setting by specifying the desired value.Global times interval: The global times that are displayed in transaction ST04 are computed based on average time distributions of samples of the active DB2 threads. By default, the samples are retrieved with the same frequency as the DB2 ZPARM STATIME. You can change this frequency by specifying a multiplier that works the same way as the history interval multiplier.

The new configuration options require the following or subsequent patch levels:
WebAS 6.20/6.40: CCMS transport SAPK640OCO and RFCOSCOL patch level 21WebAS 7.00: Basis Support Package 12 and SAPCL patch level 11Alternatively to installing the above mentioned levels, you can perform the following actions manually (for example, using the IBM tool SPUFI):Perform the following INSERTS replacing

byDB2QPROF for Release 7.00DB2PROF for Release 6.xx:For the History interval: INSERT INTO (CLKEY,CLVALUE)
VALUES ( ‘DSC_HIST_EVAL’ , ‘1′);
For Keep top N statements: INSERT INTO (CLKEY,CLVALUE)
VALUES ( ‘DSC_HIST_STMT_NO’ , ‘50′);
For Global times interval: INSERT INTO (CLKEY,CLVALUE)
VALUES ( ‘ACC_TIME_EVAL’ , ‘1′);

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