LOADCMD

Purpose

Use the LOADCMD command to define a program module to be executed as a command.

LOADCMD is a feature that lets you define your own commands; it lets you assign a command name to a program module. (The module for this program must reside in a CMS load library that you have defined with a GLOBAL command.) When you enter the command name, this module gets control and executes. It remains in storage, waiting to be run again when you enter its assigned name from either the console or the CMDSI macro or a command file (EXEC).

Operands

name

The name of the command you are defining.

member

The member of a CMS load library associated with the command you have defined. This member is the module that executes the command you have defined; it is loaded into private, free storage.

When you enter the name, GCS calls the member to run the command. Here's what your registers will contain:

Ready(nnnnn);

When you enter a command, a GCS scan routine sets up two distinct parameter lists:

• The first list is a tokenized parameter list. (Register 1 contains its address.) The parameters listed there line up on consecutive doubleword boundaries. Blanks and parentheses serve as delimiters separating each parameter. (Parentheses show up in the list, each on a doubleword boundary.)
• The second is an extended, or not tokenized, parameter list. (Register 0 contains its address.) It contains addresses that map out the extended form of a command. This extended parameter list has the following format:

  EPLMAP DC  A(CMDBEG)  ADDR OF COMMAND TOKEN
         DC  A(ARGBEG)  ADDR OF BEGINNING OF ARGUMENTS
         DC  A(ARGEND)  ADDR OF END OF ARGUMENTS
         DC  A(0)       ADDR OF EXEC FILEBLOCK
         DC  A(0)       ADDR OF FUNCTION ARGUMENT LIST
         DC  A(0)       ADDR FOR RETURN OF FUNCTION DATA
         DS  X          INDICATOR (see the following note)
         DS  3X         RESERVED

  Note: An INDICATOR byte of X'00' is a sign that a program issued the command. X'0B' is a sign that it was issued from the console. X'01' is a call from REXX when ADDRESS COMMAND is specified. X'05' is used by REXX for function calls.

Here are two ways you might enter a command and two sets of accompanying tokenized and extended parameter lists that result:

1. You enter:

      ====> loadcmd cmdname memname

   The scan routine sets up the following tokenized parameter list:

   FORMAT:  DC   CL8'LOADCMD'
            DC   CL8'CMDNAME'
            DC   CL8'MEMNAME'
            DC   8X'FF'

   The scan routine sets up the extended parameter list with the following references:

   CMDBEG  DC   C'loadcmd'
   ARGBEG  DC   C'cmdname memname'
   ARGEND  EQU  *

   The first nonblank character following ‘loadcmd’ determines the start of ARGBEG.
   Note: The tokenized parameter list is passed with uppercase characters. The extended parameter list is passed with mixed case (as entered) characters.

2. You enter ‘loadcmd’ without specifying any arguments:

   ====> loadcmd

   The scan routine sets up the following tokenized parameter list:

   FORMAT:  DC   CL8'LOADCMD'
            DC   8X'FF'

   The scan routine sets up the extended parameter list with the following references:

   CMDBEG  DC   C'loadcmd'
   ARGBEG  EQU  *
   ARGEND  EQU  *

   With no arguments specified, ARGBEG is set equal to ARGEND.
   Note: The tokenized parameter list is passed with uppercase characters. The extended parameter list is passed with mixed case (as entered) characters.

For more information on parameter lists, see z/VM: CMS User's Guide.

Usage

If the program defined by the LOADCMD is reentrant, then it is loaded into key 0 storage. This ensures that it is not accidentally modified or tampered with.

Messages

For more information on messages, see z/VM: Other Components Messages and Codes.

Return Codes