Defining Separate Facilities for Regions

The advantages of defining separate facilities for each region or group of regions are:

The TSS command allows a security administrator to specify which facilities a user can access. In other words, he can specify which CICS regions a user can sign on to.
Operating modes and logging options are specified by facility. This allows one region to be in FAIL mode while another is in WARN mode.
There are several other control options specified on a facility basis, such as LOCKTIME, which can also prove useful.
The Limited Command Facility (LCF) allows a security administrator to include or exclude transactions by facility. This allows a user who has access to both CICSPROD and CICSTEST to have access to one set of transactions for CICSPROD and another set of transactions for CICSTEST
The FACILITY parameter of the PERMIT function allows the security administrator to permit access to one set of resources (like OTRANs, PPTs, FCTs, and so on) for your CICSTEST region and another set of resources for your CICSPROD region.
The ADMIN function allows a security administrator to establish which facilities a security administrator is responsible for. This provides separate administration for each CICS region.