Hi Felicity,
Seems you are compiling with Enterprise COBOL, some OS/VS COBOL compiler options are not supported by Enterprise COBOL
The RES or NORES option is not available. With Enterprise COBOL, the object module is always treated such that library subroutines are located dynamically at run time, instead of being link-edited with the COBOL program. This is equivalent to RES behavior in OS/VS COBOL.
Please have a look to Enterprise COBOL for z/OS Migration Guide.
Please mark question as answered if you wish I gave the correct answer.
Regards,
Ollivier
Link used : http://publibfp.boulder.ibm.com/epubs/pdf/igy6mg10.pdf