To best use the resources of the cross-system coupling facility (XCF), you should first use the default transport classes and run Resource Measurement Facility (RMF™) reports with XCF usage to determine if customization is needed. If you try to establish a configuration where the hardware is on the same system where the highest needs are for that library (storage group level, OSMC processing level, or user grouping), the cross-system overhead is reduced. OAM processing in an OAMplex increases XCF resource overhead with small messages used to communicate changes in the configuration during normal processing, and larger messages for object reads or writes that require cross-system processing.
Related reading: For more information, see Using appropriate transport classes within XCF and z/OS RMF User's Guide.