Your installation is not required to use staging data sets for APPC/MVS log data. However, if a system or coupling facility failure causes the loss of APPC/MVS log data, warm/cold mismatches between local and partner LUs result. To resolve such mismatches, your installation might have to:

1. Bring down APPC/MVS (see Operating APPC/MVS for recommended methods of stopping APPC/MVS work cleanly)
2. Use RRS ISPF panels to remove the expressions of interest that APPC/MVS LUs have in units of recovery For more information, see z/OS MVS Programming: Resource Recovery.
3. Restart APPC/MVS.

This manual intervention might be more costly than the potential performance impact of using staging data sets. Because APPC/MVS infrequently writes to its log, the performance impact should be relatively slight; so consider defining the APPC/MVS log stream with STG_DUPLEX(YES) and DUPLEXMODE(UNCOND).