VSAM record-level sharing and DFSMStvs use coupling facilities to hold cached copies of individual records and to hold lock and log structures. Planning the use of coupling facilities is important to ensure that you meet your availability and performance objectives. This topic introduces some of the coupling-facility functions and provide information to help you decide the type and number of coupling facilities and how much storage you need to implement DFSMStvs.

Related reading: For more information about coupling facilities, see z/OS MVS Setting Up a Sysplex.