RE: User defined functions

You can define the function within the same source file as the program that calls it.

Here is an example:

      $set preservecase case repository(update ON)
       id division.      
       function-id. myfunction.
       linkage section.
       01 myparam    pic x(5).
       01 myresult   pic x(5).
       procedure division using myparam returning myresult.
           move myparam to myresult
           goback.
       end function myfunction.
       
       id division.
       program-id. mytest.
       environment division.
       repository.
           function MYFUNCTION.
       data division.
       working-storage section.
       01 myparameter   pic x(5) value "12345".
       01 myresult      pic x(5) value spaces.
       procedure division.
           move function myfunction(myparameter) to myresult
           display myresult
           goback.
  
       end program mytest.