Using UNIX System Services and the Hierarchical File System

z/OS® UNIX System Services (USS) gives the z/OS® operating system an open standards interface. It contains a UNIX shell and utilities, which you can use to enter shell commands, write shell scripts, and work with the file system.

z/OS® UNIX provides a Hierarchical File System (HFS) for z/OS®. A file within z/OS® UNIX is called an HFS file. HFS files are organized in a hierarchy of files and directories in a tree much like UNIX. A directory can contain files or other subdirectories.

To access the Hierarchical File System:

  1. Select option 8 (HFS) from the Primary Option Menu.

    File Manager displays the Access Hierarchical File System panel.

  2. On the Access Hierarchical File System panel, select the required option so that File Manager invokes standard ISPF services to enable access to USS and HFS utilities.

If you are familiar with File Manager functions, there is a convenient way to access HFS files. For basic functions, you can specify an HFS file in the same panels and batch commands as an z/OS® data set.

File Manager can access an HFS file as a simulated QSAM/BSAM file. This means that at the I/O level, the file is seen as a single-volume, physical, sequential data set that resides on DASD. It is allocated dynamically or referred using a DD statement (PATH parameter).

The following sections summarize the main features and differences.