CMS Operating Characteristics

CMS is a command-driven system—you enter a command, CMS runs it. The command you enter can be a CP command, a CMS command (a command that is part of the CMS system), or it can be the name of a user-written program (a program written by you, your local system programmer, or your favorite software house).

User-written programs are generally in the form of modules or execs. Modules are programs written in or compiled into machine-readable language. Execs are programs written in the Restructured Extended Executor (REXX) language. See the z/VM: REXX/VM Reference for more information on execs.