You can use the LIKEFILE keyword to indicate that a prototyped parameter is a file. When make a call using the prototype, the file that you pass must either be the file that was specified on the LIKEFILE parameter of the prototype, or it must be a file that is related through LIKEFILE File-specification keywords to that file. For example, if you specify LIKEFILE(MYFILE) on the prototype, and you have another File specification that defines file OTHERFILE using LIKEFILE(MYFILE), then you can pass either MYFILE or OTHERFILE on the call. See
For more information on file parameters and variables associated with files see the chapter about general file considerations in the "WebSphere Development Studio ILE RPG Reference."