"COBOL 85 compiler" is not a mainframe compiler. It is a reference to one of the standards for COBOL but that does not identify a version of the compiler. Enterprise COBOL, COBOL for MVS & VM, OS/390 COBOL, VS COBOL II, OS/VS COBOL -- these are all mainframe COBOL compiler versions. Notice there is not a single version (85 or any other year) listed.
The link you need to research is http://www-01.ibm.com/software/awdtools/cobol/library/