A flag in the RACF® data set name table (ICHRDSNT) enables the system for sysplex communication. When enabled for sysplex communication, a RACF system can be in one of several modes for accessing the RACF database. The mode is set by another flag in the data set name table. The mode determines whether or not RACF is to use the coupling facility. See The data set name table.

The first system to complete RACF initialization establishes the data set name table. This table remains in effect until a sysplex-wide IPL occurs or an RVARY command is issued. Subsequent systems validate their data set name table against that of the data set name table previously established. If they are compatible, the local data set name table is used. If RACF data set names do not match exactly, or backup data set option flags do not match exactly, RACF issues a message and uses the table previously established. If a mode discrepancy is detected, RACF does not issue a message but simply overrides the mode to match the table previously established.

Guideline: Use a common data set name table if you can. However, if you want to have differing numbers of in-storage buffers on different systems, you must use multiple data set name tables.

The current mode can be modified without an IPL by using the RVARY DATASHARE or RVARY NODATASHARE command. Note, however, that RVARY cannot change the bit setting in your data set name table. Therefore, you should change your data set name table mode bit so RACF comes up in the mode you want if you ever have to do a sysplex-wide IPL.