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REXX to LE

Within REXX there are four commands which can be used to invoke external routines, which could be coded in either REXX or some other language.

The instructions, which are equally valid for invoking LE and non-LE programs, are listed opposite.

In these pages the focus is on Assembler and COBOL, but both C++ and PLI are viable alternatives.

In addition to the instructions listed opposite there is a TSO RUN command, but that is not pertinent to this discussion.

REXX to LE : Invoking External Routines.

• CALL
  
  There are two types of CALL available, the REXX instruction and the TSO Command.
  
  
• LINK
  
  This is essentially a one-way process as data can be passed to the external routine, but the only information retrieved will be the return code. This is not discussed further.
  
  
• LINKMVS
  
  This provides for two-way communication, and more over the size of the data returned can vary.
  
  
• LINKPGM
  
  This provides for two-way communication, but the size of the data returned must match that of the input.
  
  This method was chosen for the following examples as it was slightly easier, and hence quicker, to implement than LINKMVS.