IBM Transaction Server OS - Manual (Page 33)

The affinity data VSAM files
The Detector uses three non-recoverable VSAM KSDS to hold saved affinity data.
Ensure the files 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 files are used because the Detector and the Reporter need keyed access to
the data.
The files are not recoverable because of the large amount of data that needs to be
written. The data is written to the files 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 file record. Records are therefore of varying length. Each record has a prefix
that contains a one-byte table identifier identifying the affinity table the record
belongs to. The table identifier acts as the first part of the record key. The second
part of the key is the key of the table element itself.
Each file contains a header record. This enables both the Detector and the
Reporter to validate that the files they have been presented with are indeed data
files suitable for the Transaction Affinities Utility. The header record has a key in the
same format as the rest of the keys on the file, so a table identifier of zero is used
(no real table will have a table identifier of zero). The header record contains the
CICS specific applid, thus allowing files to be cross-validated.
The control record VSAM file
The Transaction Affinities Utility control file is a recoverable VSAM KSDS file 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 first run on the CICS region, and is never deleted.
The control record holds the following information:
v CAFF options
v Detector statistics
v History 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
– Specific 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 definition for the control record VSAM file makes it recoverable
to CICS. You can change the definition if you do not require recovery. See
“Defining the VSAM files to CICS” on page 22 for more information.
Chapter 2. Introducing the Transaction Affinities Utility 17