Defining Multiple Systems Coupling resources

Before you can define MSC resources dynamically, both MSC and dynamic definition for MSC must be enabled in the IMS system. MSC is enabled either by specifying the MSC= execution parameter in the IMS startup procedure or by defining at least one MSC link with stage-1 system definition macros during IMS system definition. Dynamic definition for MSC is enabled by specifying MSCRSCS=DYN in the MSC section of the DFSDFxxx PROCLIB member.

After MSC and dynamic definition is enabled, you can create, update, and delete MSC resources by using IMS type-2 commands, such as CREATE MSPLINK, UPDATE MSPLINK, and DELETE MSPLINK. To save changes to MSC resources that are made dynamically across a cold start, either export the definitions to the IMSRSC repository or code the changes to the MSC resources into stage-1 system definition macros. To delete resources from the IMSRSC repository, issue the DELETE DEFN command. Otherwise, changes to MSC resources that are made dynamically are saved across warm and emergency restarts only. MSC does not support resource definition data sets (RDDSs).

If you define MSC resources statically during IMS system definition, you do not need to specify the MSC startup parameter, although doing so can avoid confusion. To enable MSC in an IMS online system by using static definitions only, your IMS system definition must include three macros: MSPLINK, MSLINK, and MSNAME.

You also need to define transaction codes for each IMS system that has any part in transaction entry or processing. You can define transaction codes dynamically or by using system definition macros. An individual system can play several roles: it can be the input system, it can be an intermediate system responsible for routing transactions, or it can be a destination system in which the transaction is processed.

Using MFS is the same in an MSC network as in a single-system environment. If a message is created in one IMS for a terminal that is attached to another IMS, the required message and format descriptions must be available to the IMS to which the terminal is attached, and definitions with the same name must be defined identically in each IMS.