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.