The unified software for z/OS provides a choice of deployment
               environments, either: 
            
            
               -  Hierarchical file system (HFS) or z/OS Distributed File
                  Service zSeries File System (zFS) files on UNIX System Services.
                  (This manual uses the term "HFS" generically to refer to both the
                  HFS and the zFS file systems, except where explicitly stated otherwise.)
               
 
               -  Partitioned data set (PDS) libraries. 
 
            
            To compare their benefits, see Choosing
                  How to Deploy.