The systems sharing a TKDS may be different LPARs on the same system or different systems across multiple zSeries processors. It is not required to share the TKDS across a sysplex. Each system may have its own TKDS. A sysplex may have a combination of systems that share a TKDS and individual systems with separate TKDSs. There is no requirement that the DOMAINs must be the same to share a TKDS. When sharing the TKDS, a few precautions should be observed:

• Dynamic TKDS services update the DASD copy of the TKDS and the in-storage copy on the system where it runs. The SYSPLEXTKDS option in the ICSF installation options data set provides for sysplex-wide consistent updates of the DASD copy of the TKDS and the in-storage copies of the TKDS on all members of the sysplex sharing the same TKDS.

  If SYSPLEXTKDS(YES,FAIL(xxx)) is coded in the installation options data set, a sysplex broadcast message will be issued informing sysplex members of the TKDS update and requesting them to update their in-storage TKDS copy. If SYSPLEXTKDS(NO,FAIL(xxx)) is coded in the installation options data set, there is no sysplex broadcast of the update.

• If multiple sysplexes share a TKDS, or if a sysplex and other non-sysplex systems share a TKDS, there is no provision for automatic update of the in-storage copies of the TKDS on the systems which are not in the same sysplex as the system initiating the TKDS update.