Use the IXGWRITE service to write data from the user's buffer to a log stream. The way system logger processes an IXGWRITE request depends on whether the log stream is coupling facility or DASD-only:
For coupling facility log streams, system logger writes the data to the coupling facility structure space associated with the log stream when an IXGWRITE request is issued. System logger also duplexes the data to either local storage buffers or staging data sets.
For DASD-only log streams, system logger writes the data to interim storage in local storage buffers for the system associated with the log stream. It is simultaneously duplexed to DASD staging data sets. The safe import point for a DASD-only log stream is changed for every successful write request.