Addressing OLTP Solutions with CICS: The Transaction Server ... - Ibm

Table 7. Dynamic and Static Registration
Dynamically Registering
Relational Database
against the XA-enabled database will fail. CICS only catches the database
failure if a new CICS application server is started. CICS must be shut down
before the database is brought back online after recovery. If you attempt an
automatic start of the CICS region before the database has been recovered, the
region abends.
With statically registering XA-enabled relational databases such as Oracle and
Informix, all CICS transactions in the region will make XA calls even though
some transactions do not have to access the database. When the relational
database suffers a catastrophic failure, CICS catches the failure and immediately
abends the region. You cannot warm start the CICS region until the database
has been recovered, otherwise the region will abend.
If the majority of your CICS transactions do not have to access a database, we
strongly recommend that you use a database that supports XA dynamic
registration such as DB2 for AIX. In this way, CICS can arrange to drive
syncpoint in the database only when the database is actually updated for a given
transaction. This can reduce the time it takes to syncpoint a transaction when
running in an environment with multiple XA databases and CICS control files,
where transactions usually only update data managed by some of the
applications.
Table 7 compares dynamic and static registration.
Only a CICS application that issues SQL calls
makes an XA call.
In the case of catastrophic failure of the
database, CICS transactions accessing that
database fail. The other CICS applications
continue to run. CICS abend is deferred until
the next application server (cicsas) is started
and CICS detects the database failure during
opening of the connection.
Shorter syncpoint processing time because the
resource manager is invoked only to commit or
roll back when the data it manages changes
7.3 Using DB2 for AIX as CICS File Manager
Statically Registering
Relational Database
Every CICS application makes an XA call.
In the case of catastrophic failure of the
database, the CICS for AIX region immediately
abends. The database has to be recovered
before CICS can be started up again.
Syncpoint processing time is longer because
the resource manager is invoked every time
regardless of whether the data it manages
changes or not.
With CICS for AIX Version 2.1 and later, you can use a DB2 for AIX database for
CICS file management instead of a local or remote Encina SFS. CICS file
management refers to the management of data associated with user files,
auxiliary temporary storage queues, intrapartition transient data queues, and
locally queued ATI requests. In simple terms, this enhancement is a mapping
function of the CICS for AIX SFS files to DB2 for AIX tables. CICS applications
maintain the same logical views of these files, that is, as though they were SFS
Chapter 7. Interactions with the DB2 Family of Products 95