PDSE data sets and members can be shared. If allocated with DISP=SHR, the PDSE directory can be shared by multiple writers and readers, and each PDSE member can be shared by a single writer or multiple readers. Any number of systems can have the same PDSE open for input. If one system has a PDSE open for output (to create or replace members), that PDSE can be opened on other systems only if the systems are using the PDSE extended sharing protocol. The storage administrator can establish PDSE extended sharing protocol by using the PDSESHARING keyword in the IGDSMSxx member of SYS1.PARMLIB as described in z/OS DFSMSdfp Storage Administration.