Do I have to recompile or re-link my COBOL applications to move to z/OS from OS/390?
Answer: No. Moving from OS/390 to z/OS is very much like moving from one release of OS/390 to another. Your COBOL applications will run unchanged on z/OS just like they would run on OS/390 V2R10.0.
Does COBOL run in 64-bit z/OS?
Answer: Yes. Though COBOL does not support 64-bit addresses 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.
Will there be a version of COBOL and/or the BINDER that will create 64-bit COBOL load modules to run under z/OS?
Answer: We are in the process of evaluating the addition of 64-bit addressing support in COBOL. The BINDER already supports 64-bit assembler programs and will support 64-bit C/C++ programs in the future. We have heard of very few customers requiring 64-bit addressing in COBOL programs. If you have a need for AMODE 64 COBOL, or mixing AMODE 64 C/C++ with AMODE 31 COBOL, similar AMODE type requirements, please send your requirements to us with details. There are many directions we could go from this point. For example, would a COBOL compiler that would only create AMODE 64 programs that could not be mixed with AMODE 31 programs be useful? Would a solution that involved taking advantage of C/C++ AMODE 64 be useful? What would you use AMODE 64 COBOL for? Please use the Contact z/OS link below.