Understanding VSAM RLS
Record level sharing (RLS) is a VSAM function provided by DFSMS/MVS™ Version 1 Release 3 that is exploited by the CICS® Transaction Server. RLS lets VSAM data sets be shared, with update capability between many applications in many CICS® regions.
With VSAM RLS, CICS® regions that share VSAM data sets can reside in one or more MVS™ images within an MVS™ parallel sysplex. Whether or not the data set is accessed as an RLS data set is determined at OPEN time by the ACB macro setting or by a JCL parameter. To enable RLS, use the MACRF=RLS ACB macro setting.
CICS® VR can recover VSAM data sets accessed in RLS-mode; however, CICS® VR VSAM batch logging cannot perform logging for VSAM data sets that are accessed in RLS mode. See Setting up CICS VR VSAM batch logging for more information.