The z/OS NFS server handles data set serialization and sharing differently depending on the type of data set:

Physical sequential

The server insures the read/write integrity of a physical sequential data set by SVC 99 dynamic allocation with exclusive option whenever a physical sequential data set is opened for output; otherwise it is allocated with share option.

VSAM data set

The server dynamically allocates a VSAM data set with share option and allows the VSAM access method to manage data sharing using the SHAREOPTIONS specified during data set definition.

PDSE data set

The server dynamically allocates a PDSE data set with share options and allows the PDSE functions to manage the integrity of the PDSE data set and its members.

PDS data set

The server dynamically allocates a PDS data set with share option and surrounds the PDS and its members with exclusive ENQs against the QNAME=SPFEDIT and RNAME=data set name. This does not protect the PDS from other z/OS users who are attempting to access the PDS without performing ENQ against SPFEDIT similar to the z/OS NFS server.