Global Cardholder Synchronizer (GCS) is a role that synchronizes shared cardholders and other related entities between a local system (sharing guest) and a central system (sharing host).
The GCS role on a sharing guest system requires a dedicated user on the sharing host system to connect. The dedicated user should not be an administrator of the entire system. Instead, grant minimum required privileges and access rights to the sharing guest. To do this, configure the user as a partition administrator only for the shared partitions that the user will access from the sharing host system.