I have been tasked with reviewing our CICS LSR buffers and to perform any tuning as required. As part of my research I wanted to use the SYSView panels as an initial starting point to address those with the worst lookaside rates. However, as I look through the associated panels, data seems inconsistent. For example, I have a single file defined to LSRPool2 in a region. LSRPools shows a lookaside PCT of 0, with 174K reads and 0 lookaside hits. I selected the Buffer display for the pool and I see 174K reads with 0 Lookasides. I select VSam to view the detail. This shows 457K reads with 174K DExcps. To me this means data is being incorrectly rolled up. These are the 3 displays: LSRPOOLs, LSRBUFF and VSAM File performance:
After review of the code I can tell you that the REQUESTS column includes Retrieves, Updates, Inserts, Deletes, and Extends. The READS column represents Retrieves only. These statistics are the values taken since the file was opened.
The DExcp count is obtained directly from IBM VSAM control blocks for the dataset. As noted in help these are the DATA EXCP's,. Also, the IExcp shows the INDEX portion of the VSAM dataset. These are also real time values, unlike a LISTCAT would only provide stats from the last open or close on the file.
Development has also indicated if you are reading data sequentially, you most likely will not get many Look Aside hits and you can also be flushing the buffers which would also result in lake of LkHits
At this point it sounds like there may need to be additional vsam tuning.