z/OS UNIX Files

z/OS UNIX System Services (z/OS UNIX) enables z/OS® to access UNIX files. UNIX applications also can access z/OS data sets. You can use the hierarchical file system (HFS), Network File System (NFS), z/OS File System (zFS), and temporary file system (TFS) with z/OS UNIX. You can use the BSAM, QSAM, BPAM, and VSAM access methods to access data in UNIX files and directories. The object access method (OAM) can also store object data in z/OS UNIX files in a zFS or NFS file system. z/OS UNIX files are byte oriented, similar to objects.

Hierarchical file system: You can define an HFS data set on the z/OS system. Each HFS data set contains a hierarchical file system. Each hierarchical file system is structured like a tree with subtrees, which consists of directories and all its related files. HFS data sets must reside on DASD volumes.
Network File System: An NFS is a distributed file system that enables users to access UNIX files and directories that are located on remote computers as if they were local. NFS is independent of machine types, operating systems, and network architectures.
z/OS File System: A zFS is a UNIX file system that supports multiple file systems in a data set.
Temporary file system: A TFS is stored in memory and delivers high-speed I/O. A system programmer can use a TFS for storing temporary files.

Related reading: For more information on z/OS UNIX files and HFS data sets, refer to the following publications: