If you are running more than one CICS system in the same MVS™ image, you may use the same CSD file to define your resources to both systems. This helps you to ensure that each system has the same definition of resources where necessary. You probably do not want to use all the same resources in each system, so you could create a list for each system. You name the appropriate list in the system initialization parameter for each system.
For example, you might have two production CICS systems sharing a CSD file. Assume that one production system runs three applications: customer inquiry, billing, and adjustments. Each application has its own resources (programs, map sets, and transactions), so you put the resource definitions in three groups: CUSTINQ, CUSTBILL, and CUSTADJ. Then you add these groups to a list called CICS1A.
Another production system runs two more applications in addition to customer inquiry: customer update and customer credit authorization. For these, you create two more groups (CUSTCRED and CUSTUPDT) and another list called CICS1B.
CICS1B contains the same CUSTINQ group as CICS1A, and it also contains CUSTCRED and CUSTUPDT. If you decide, for performance reasons, to move one of your applications to a different CICS system, all you need to do is add the appropriate group name to the appropriate list. The next time you initialize CICS with this list specified in the GRPLIST system initialization parameter, you install the new group.