The amount of space that you allocate for the two DFSMShsm log data sets depends on the amount of DFSMShsm activity at your site and how often you want to swap and print the logs. Initially, on a 3390 device, you should allocate two cylinders as the primary space allocation and one cylinder as the secondary space allocation: SPACE=(CYL,(2,1)). If your log data sets are automatically swapped too frequently, increase the primary and secondary space allocation.