Any application (for example, Interactive System Productivity Facility (ISPF) option 3.4I or DCOLLECT) that requests size information about HFS file system requires OMVS to service that request. This means that the user ID must be defined to OMVS and have Resource Access Control Facility (RACF®) authority to access the data set. The HFS file system must be either mounted on this file system or mountable (that is, not already mounted READ/WRITE on another system).