A limit applies to control units in a priority group
You can place a limited number of control units in the same priority group. The number of associated channels determines the limit. The exact number of the limit depends on the types of channels. The limit is a fixed value independent of the configuration. The CHPID Mapping Tool informs you if the number of control units in the same priority group exceeds the limit.
The number of CHPIDS in a single group that can be spread across cards for availability has a physical limit. . For example, for an IOCP with 256 ESCON channels, it might seem easiest to put all control units in a single group. However, doing so is not feasible because the machine would need 256 separate ESCON cards.