I am analyzing performance issue in a IMS transaction which issues about 15K to 20K DB2 SQLs. The customer has upgraded DB2 to version 11 in the mid of Sep-2017 and we are noticing increase in average CPU time/transaction since Sep-2017. DBA feels that the increase in average CPU time/transaction should be due to the data growth in the tables involved in the transaction and application changes implemented in production. DBA points out that if Db2 upgrade is causing issue, then it should have caused CPU increase in the all other applications, but other applications are running fine, so there is no issue with the Db2 upgrade.
This transaction invokes about 12 COBOL sub programs. I tried to find if the code changes and data growth are contributing to CPU increase, but i could not find convincing answer for the same. Packages which has not gone thru any code changes since Aug-2017, are also reporting increase in CPU time.I also noticed that BP7 GETPAGE/UPDATE has increased from 0.5 million(on May-2017) to 600+ million (on Jun-2017) and it continues to grow or shrink based on volume of transaction. There were no code changes implemented in Jun-2017 and I could not correlate data growth with BP7.
Could you please help me how to approach this issue ?