IBM OS manual The affinity data VSAM les, The control record VSAM le

The affinity data VSAM ®les

The Detector uses three non-recoverable VSAM KSDS to hold saved affinity data. Ensure the ®les are big enough to hold the maximum amount of affinity data that might be collected. Three are required because of the wide range of key lengths that the different tables have.

KSDS ®les are used because the Detector and the Reporter need keyed access to the data.

The ®les are not recoverable because of the large amount of data that needs to be written. The data is written to the ®les in such a way that it remains consistent.

When the data contained in the tables is saved, each element in each table is a single ®le record. Records are therefore of varying length. Each record has a pre®x that contains a one-byte table identi®er identifying the affinity table the record belongs to. The table identi®er acts as the ®rst part of the record key. The second part of the key is the key of the table element itself.

Each ®le contains a header record. This enables both the Detector and the Reporter to validate that the ®les they have been presented with are indeed data ®les suitable for the Transaction Affinities Utility. The header record has a key in the same format as the rest of the keys on the ®le, so a table identi®er of zero is used (no real table will have a table identi®er of zero). The header record contains the CICS speci®c applid, thus allowing ®les to be cross-validated.

The control record VSAM ®le

The Transaction Affinities Utility control ®le is a recoverable VSAM KSDS ®le that holds a single control record. This record is used to preserve the Detector options and statistics, so that information is retained across Detector runs, transaction failures, and system failures and restarts. The record is created when the Detector transaction is ®rst run on the CICS region, and is never deleted.

The control record holds the following information:

vCAFF options

vDetector statistics

vHistory information

±Reason why STOPPED

±Userid if STOPPED by user

±Abend code if STOPPED by abend

±Userid for last Detector options update

±Date and time of last Detector options update

±Speci®c applid of CICS system

The record is updated whenever any of the above information changes. This will happen when the Detector options change, the Detector statistics change, or the Detector state changes to STOPPED.

Note: The supplied de®nition for the control record VSAM ®le makes it recoverable to CICS. You can change the de®nition if you do not require recovery. See ªDe®ning the VSAM ®les to CICSº on page 22 for more information.

Chapter 2. Introducing the Transaction Affinities Utility 17