CICS attachment facility

The Customer Information Control System (CICS®) Transaction Server provides the CICS attachment facility, which lets you access Db2 from CICS.

CICS operations, application programming, and system administration and operations organizations can use the CICS attachment facility.

CICS operations

After you start Db2, you can operate Db2 from a CICS terminal. You can start and stop CICS and Db2 independently, and you can establish or terminate the connection between them at any time. You can also allow CICS to connect to Db2 automatically.

The CICS Transaction Server also provides CICS applications with access to Db2 data while operating in the CICS environment. Any CICS application, therefore, can access both Db2 data and CICS data. In the case of system failure, CICS coordinates recovery of both Db2 data and CICS data.

The CICS attachment facility uses standard CICS command-level services where needed.

EXEC CICS WAIT EXEC CICS ABEND

A portion of the CICS attachment facility executes under the control of the transaction issuing the SQL requests. Therefore these calls for CICS services appear to be issued by the application transaction.

With proper planning, you can include Db2 in a CICS XRF recovery scenario.

Application programming

Application programmers who write CICS command-level programs can use the same data communication coding techniques to write the data communication portions of application programs that access Db2 data. Only the database portion of the programming changes. For the database portions, programmers use SQL statements to retrieve or modify data in Db2 tables.

To a CICS terminal user, application programs that access both CICS and Db2 data appear identical to application programs that access only CICS data.

Db2 supports this cross-product programming by coordinating recovery resources with those of CICS. CICS applications can therefore access CICS-controlled resources as well as Db2 databases.

Function shipping of SQL requests is not supported. In a CICS multi-region operation (MRO) environment, each CICS address space can have its own attachment to the Db2 subsystem. A single CICS region can be connected to only one Db2 subsystem at a time.

System administration and operations

An authorized CICS terminal operator can issue Db2 commands to control and monitor both the attachment facility and Db2 itself. Authorized terminal operators can also start and stop Db2 databases.

Even though you perform Db2 functions through CICS, you need to have the TSO attachment facility and ISPF to take advantage of the online functions supplied with Db2 to install and customize your system. You also need the TSO attachment to bind application plans and packages.