The CALL CONVENTION _should_ be pretty transparent to the application programmer. Most calls will look the same in any dialect of COBOL. Some calls have a RETURNING field in some dialects. But I think the most common reason for specifying a CALL CONVENTION in a program would be that it is operating in an environment where more than one operating system may be used ... such as DOS and Windows.
Try the MicroFocus Help line; they are very good, in my opinion.
Ahhhhh... looking again at your code, I see that you have
CALL WINAPI ARCHLUWCOMM USING....
WINAPI tells the compiler which CALL CONVENTION to use, ARCHLUWCOMM is the program being called.
By the way, you realize that you must have the called program in your new environment, otherwise the call will not work.
You might get more help in the comp.lang.cobol newsgroup; a large number of the participants there are experts in the various PC COBOL dialects.
Stephen J Spiro
Member, J4 COBOL Standards Committee
check it out at
stephenjspiro at hotmail.com