If more than one CMAS is involved in managing a CICSplex they must all be able to communicate with each other in order to implement single-system image. This communication is also required to allow proper distribution of CICSPlex® SM definitions from the maintenance point CMAS to other CMASs and to maintain the dynamic CICSplex topology. The maintenance point CMAS is responsible for maintaining the CICSplex definitions in the data repository as well as distributing them to other CMASs.
Unlike the CASs in a network, however, CMASs need not be fully interconnected. The CICSPlex SM communications component can deliver a request for remote processing even if the target is not directly connected to the CMAS or MAS where the request originates. The minimum requirement is that you can get from every CMAS to every other CMAS in the network via some route of CMAS-to-CMAS links, no matter how complex. Of course, performance may suffer if excessive transit nodes (those CMASs through which a request must pass on its way to the desired destination) are involved in a request. As a result, more than the minimum number of required communication links are often installed.
Because each CMAS can participate in the management of one or more CICSplexes, it is important for the CAS to know what CICSplexes a CMAS can process requests for. A CMAS provides this information to the CAS during its initialization. The CMAS registers its name and the name of each of the CICSplexes it can manage. The CMAS can also inform the CAS of any changes in the CICSplexes it is managing while it is running. The CAS calls these registered names service points.
The CMAS provides the same information about its CICSplexes to the ESSS address space that is running in its MVS™ image. This is necessary because ESSS establishes the connection between a CMAS and its local MASs. This connection is normally established when the MAS provides its name and the name of the CICSplex it is a member of. So ESSS must be able to find a CMAS that manages the CICSplex named by a MAS.
Figure 5 shows a sample CMAS network and the service points that result.
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