z/OS

Does COBOL run in 64-bit z/OS®?

Yes. Though COBOL does not yet support 64-bit addressing in COBOL programs, you will get some of the benefits of 64-bit z/OS just by moving to it. With a 64-bit addressable real memory backing your virtual memory, there will be less paging and swapping and therefore better system performance, and you don't have to change your programs at all! In addition, Db2® can exploit 64-bit addressing for SQL statements in COBOL programs without any changes to the COBOL programs.

Even when your z/OS system is running in 64-bit mode, you can still run existing AMODE 24 and AMODE 31 applications without having to relink or recompile them. You can get improved system performance without any changes to your applications.