Understanding the affinities

The inter-transaction affinities listed in the report highlight those transactions that have affinities with other transactions.

Understanding the affinities present in the CICS® region enables you to determine which of the them are most pervasive. If you decide that it is worth changing your application programs, it is generally more cost-effective to remove the most pervasive affinities, because those affinities most restrict dynamic routing. The most pervasive affinities are those with a relation of GLOBAL, or a lifetime of SYSTEM or PERMANENT, and are heavily used.

The transaction-system affinities listed in the report highlight those transactions that use system programming commands. It might not be appropriate to dynamically route such a transaction, because its action might be tied to a particular CICS region, as opposed to a particular set of other transactions.

The affinity report also lists affinities occurring between transactions that were not initiated from a terminal and are not BTS or Link3270 bridge transactions. These background transactions are known as "background relations". This information is really for completeness, because such transactions cannot be dynamically routed.

To obtain complete information on affinities, use as many code paths as possible while running the Collector, because it can find an affinity only if the commands that cause it have been executed. However, the Load Module Scanner detects all instances of affinity commands in the corresponding load library. So a comparison of the Affinities Reporter and Load Module Scanner outputs is very useful when establishing the full picture.

Important note

Both the Affinities Reporter and the Load Module Scanner might identify commands that, on closer examination, do not cause real affinities. Relate the output from the Reporter and the Load Module Scanner to your knowledge of your applications, to distinguish between such commands and those causing real affinities that impact CICS dynamic routing.