Troubleshooting
Problem
You convert a VSAM dataset to Record Level Sharing (RLS) and now your Execute Channel Program (EXCP) count for the dataset increases within CICS Transaction Server for z/OS (CICS TS).
Symptom
EXCP statistic fields A17DSIXP ( INDEX EXCP ) and A17DSXCP ( DATA EXCP ) increase when converting a VSAM dataset to RLS.
Cause
RLS increments the EXCP count in buffer code. Whenever buffer management gets called RLS will raise the count by one. Every request gets counted whether it is ultimately satisfied by cache, dasd, or buffer.
So for 100 EXEC CICS READs. you will statistically receive 100 EXCPs for both data and index since it takes one buffer request to each set of buffers to ensure RLS has the right record to return. The EXCP number goes up if RLS has to re-drive the request for any reason.
For EXEC CICS WRITE the situation gets much more complicated. RLS increments the EXCP counter for every buffer write. However, as part of WRITE processing RLS often does requests behind the scenes, such as locate.
For RLS, not all EXCPs are DASD I/O hits.
Resolving The Problem
To determine how many EXCPs are hitting DASD, you can monitor the SMF42 records, subtypes 15, 16, or 19, or you can use RMF Monitor III. These all give a breakdown of all the RLS requests to buffer, cache, or dasd.
Product Synonym
CICS/TS CICS TS CICS Transaction Server
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Document Information
Modified date:
15 June 2018
UID
swg21496312