z/OS UNIX responds to requests from programs and the shells. z/OS UNIX has two shells, the z/OS shell and the tcsh shell. They are collectively called the z/OS UNIX shell. The interactive shell interface is an execution environment analogous to TSO/E, with a programming language of shell commands analogous to the Restructured eXtended eXecutor (REXX) Language. The shell work consists of:

• Programs run by shell users
• Shell commands and scripts run by shell users
• Shell commands and scripts run as batch jobs