You can connect more than one CICS® system to the same DB2® system. However, the CICS DB2 attachment facility does not allow you to connect one CICS system to more than one DB2 system at a time.
You can set up production and test environments with:
The first alternative, using a single CICS system for both production and test, is not recommended. In releases of CICS before CICS Transaction Server for OS/390®, Version 1 Release 2, this was not recommended because the RCT could not be dynamically changed. You can now change the CICS DB2 definitions using RDO without stopping the attachment facility. Programs, transactions, maps, terminals and DB2 definitions can all be dynamically added to a running system. However, this environment is still not recommended, because applications in test could affect the performance of the production system.
The second alternative, with just one DB2 system, could be used for both test and production. Whether it is suitable depends on the development and production environments involved. Running a test CICS system and a production CICS system separately allows test failures without impacting production.
The third alternative, with, for example, one test and one production DB2 system, is the most flexible. Two CICS subsystems can run with one or more DB2 systems. Where the CICS systems are attached to different DB2 systems: