You can run PCF and ICSF simultaneously on the same z/OS system or separately in three different modes. You can run ICSF in compatibility, coexistence, or noncompatibility mode.

In compatibility mode, you can run either PCF or ICSF, but you cannot run them simultaneously on the same z/OS system. You can continue to run PCF applications on PCF or you can run PCF applications on ICSF. ICSF supports the PCF macros that the PCF applications call. However, you cannot run the PCF key generator utility program (KGUP) on ICSF. You do not have to reassemble PCF applications to run the applications on ICSF.

In coexistence mode, you can run PCF and ICSF simultaneously on the same z/OS system. You can continue to run a PCF application on PCF or you can reassemble the PCF application to run on ICSF. In this mode, ICSF supports the PCF macros when a reassembled PCF application calls these macros.

In noncompatibility mode, you can run PCF and ICSF simultaneously and independently on the same z/OS system. You can run PCF applications on PCF and ICSF applications on ICSF. You cannot run PCF applications on ICSF, because ICSF does not support the PCF macros in this mode.

You can run PCF simultaneously and independently in coexistence and noncompatibility mode. Therefore, in these modes, you can run PCF KGUP on PCF while running ICSF. The PCF KGUP updates keys on a PCF CKDS.

The ICSF installation option COMPAT(YES, COEXIST or NO) allows you to specify which mode you want ICSF to run in. You specify COMPAT(YES) for compatibility mode, COMPAT(COEXIST) for coexistence mode, and COMPAT(NO) for noncompatibility mode. See Steps to create the Installation Options Data Set for information about creating the installation options data set and Parameters in the installation options data set for details about these options.