For both coupling facility and DASD-only log streams, you must plan the number of log streams required by system logger applications for your installation based on the kinds of logger applications you plan to have and the type of log stream, coupling facility or DASD-only. For example, one application might run on multiple systems in the sysplex and require a single sysplex-wide log stream. For another application running on multiple systems, you might want a separate log stream for each system.

For OPERLOG and logrec log streams, if you want to merge data from across the sysplex, you define one coupling facility log stream for the sysplex, written to by all the systems.