Question: 

What is the difference between VSAM RLS and SYSB-II?

Answer: 

VSAM RLS gives you the ability to define VSAM files (data sets) as either "recoverable" or "non-recoverable." If the files are defined as non-recoverable, you can process batch while the files are still available to CICS. However, non-recoverable files do not support forward or backward recovery. Therefore, you should not define files that contain critical data as non-recoverable.

VSAM RLS is not a substitute for SYSB-II. SYSB-II can run with or without VSAM RLS.

To learn more, read the VSAM RLS briefing.