For a DASD-only log stream, offloading of log data to DASD log data sets is always triggered by staging data set usage. System logger off-loads data from local storage buffers to DASD log data sets when it hits the high threshold defined for the staging data sets. For example, if you define a high threshold of 80% for a DASD-only log stream, system logger will begin offload processing when the staging data set space defined for a log stream reaches or exceeds 80% usage.

This means that if you size your staging data sets too small, system logger will offload log data from local storage buffers to DASD log data sets frequently, incurring overhead. You might also run the risk of filling the staging data sets up completely. If this occurs, system logger will immediately begin offloading log data to DASD log data sets.