z/OS TSO/E REXX Reference
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Using SYSPROC and SYSEXEC for REXX execs

z/OS TSO/E REXX Reference
SA32-0972-00

In the module name table, the LOADDD field contains the name of the DD from which REXX execs are fetched. The default TSO/E provides for non-TSO/E, TSO/E, and ISPF is SYSEXEC. If you customize REXX processing either by providing your own parameters modules or explicitly calling IRXINIT to initialize an environment, it is suggested that you use the ddname SYSEXEC. The TSO/E REXX documentation refers to this DD as SYSEXEC. For a description of LOADDD field, see Module name table.

In TSO/E, you can store both interpreted and compiled REXX execs in data sets that are allocated to either SYSPROC or SYSEXEC. You can use SYSPROC for both TSO/E CLISTs and REXX execs. SYSEXEC is for REXX execs only. If an exec is in a data set that is allocated to SYSPROC, the exec must start with a comment containing the characters REXX within the first line (line 1). This is referred to as the REXX identifier and is required in order for the TSO/E EXEC command to distinguish REXX execs from CLISTs. z/OS TSO/E REXX User's Guide describes how to allocate execs to SYSPROC and SYSEXEC. For information about compiled execs, see the appropriate compiler publications.

In the parameters module, the NOLOADDD flag (see Flags and corresponding masks) controls the search order for REXX execs. The flag indicates whether the system searches the DD specified in the LOADDD field (SYSEXEC). With the defaults that TSO/E provides, the system searches SYSEXEC first, followed by SYSPROC. The system searches SYSPROC only if the language processor environment is integrated into TSO/E.

If your installation plans to use REXX, store your execs in data sets that are allocated to SYSEXEC, instead of using SYSPROC. Using SYSEXEC makes it easier to maintain your REXX execs. If your installation uses many CLISTs and does not plan to have a large number of REXX execs, you may want to use SYSPROC only and not use SYSEXEC. To use SYSPROC only, you might provide your own IRXTSPRM parameters module for TSO/E or use the EXECUTIL SEARCHDD command.

If you provide your own IRXTSPRM parameters module, specify the following values for the NOLOADDD mask and flag fields:
  • NOLOADDD_MASK — 1
  • NOLOADDD_FLAG — 1

With these values, the system does not search SYSEXEC and searches SYSPROC only. You can make your parameters module available on a system-wide basis for your entire installation. You can also make your module available only to a specific group of users by making it available only on a logon level. You can place your IRXTSPRM module in a data set specified in the STEPLIB concatenation in the logon procedure. You must ensure that the data set is higher in the concatenation than any other data set that contains IRXTSPRM. See z/OS TSO/E Customization for more information about logon procedures.

You need not provide your own IRXISPRM parameters module for ISPF because the NOLOADDD mask value in the default IRXISPRM module is 0, which means IRXINIT uses the flag setting from the previous environment. In this case, the previous environment is the value from the IRXTSPRM module you provide.

You can also use the EXECUTIL command with the SEARCHDD operand to change the search order and have the system search SYSPROC only. You can use EXECUTIL SEARCHDD(NO) in a start-up CLIST or REXX exec that is part of a logon procedure. Users can also use EXECUTIL SEARCHDD(NO) to dynamically change the search order during their TSO/E and ISPF sessions. For more information about the EXECUTIL command, see TSO/E REXX commands.

In TSO/E, you can also use the TSO/E ALTLIB command to define alternate exec libraries in which to store implicitly executed REXX execs. Using ALTLIB, you can specify alternate libraries on the user, application, or system level and activate and deactivate individual exec libraries as needed. For more information about using ALTLIB, see z/OS TSO/E REXX User's Guide.

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