Syntax:  SET ROUTINE PARAMETER parameter_name optional_or_required
              mechanism add_remove defined_routine defined_package

  Specifies a parameter to the given routine.

  When a routine is expanded, its parameters will appear in the routine
  call template as placeholders, which can be substituted just as
  regular placeholders.

  You can specify the passing mechanism or the parameter, as well as
  whether or not the parameter is required; the text processing utility
  (TPU) routine, which generates the placeholder for this parameter,
  uses these attributes to determine the form of the placeholder.

  Routine parameters are positioned by the order in which they are
  defined.  Consider the following example to define a routine:

  F (A, X, Y)

  Enter the following commands:

  SET ROUTINE PARAMETER A REQUIRED VALUE ADD [ ] [ ] SET ROUTINE
  PARAMETER X OPTIONAL VALUE ADD [ ] [ ] SET ROUTINE PARAMETER Y
  OPTIONAL VALUE ADD [ ] [ ]