Using UNIX System Services and the Hierarchical File System

z/OSĀ® 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.

    Z Data Tools displays the Access Hierarchical File System panel.

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

If you are familiar with Z Data Tools 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.

Z Data Tools 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.