IBM OS manual Understanding the affinities, Modifying affinity transaction groups

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 may not be appropriate to dynamically route such a transaction, because its action may 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 or are not CICS BTS transactions. These background transactions are known as background relations. This information is really for completeness, because such transactions cannot be dynamically routed.

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

Important note

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

For more information about interpreting the affinity report, see ªAppendix C. Useful tips when analyzing Transaction Affinities Utility reportsº on page 75.

Modifying affinity transaction groups

Consider making the following modi®cations to the affinity transaction groups before inputting them to the Builder:

vRemove false affinities

False affinities may arise because the sharing of a resource is done on a read-only basis, so it is possible for the resource to be replicated across cloned CICS regions. The prime example of this is a read-only CWA, where the CWA is set up at CICS startup (for example, from a PLTPI program), and only ever read thereafter. (An alternative way of removing this false affinity is to prohibit detection of ADDRESS CWA by the Detector using the CAFF options.)

vRemove affinity relation worsening

An affinity that has a relation of LUNAME, BAPPL,or USERID may be worsened

to GLOBAL because the Detector has not seen enough examples of the affinity

48 CICS Transaction Affinities Utility Guide