Using global resource serialization with cartridge entry processing

Cartridge entry processing is usually serialized; that is, one system performs cartridge entry for the entire SMS complex. This is accomplished by using global resource serialization (GRS) with a SYSTEMS level enqueue.

The resource names are as follows:

QNAME-SYSZCBR
RNAME-CARTRIDGE_ENTRY_libname

If the library is a PtP VTS, the libname represents the composite library.

Note: OAM already performs a SYSTEMS level enqueue for global resource serialization. If you are using IBM global resource serialization ring or star support, you do not need to include the QNAME or RNAME in the SYSTEM inclusion RNL. The QNAME and RNAME are provided for documentation purposes. If a GRS-equivalent product is being used, refer to that product documentation to ensure that the SYSTEMS level enqueue is honored and for any setup that might be needed to propagate the enqueue across your systems.

It is possible to perform cartridge entry processing without global resource serialization. The consequences of unserialized processing are as follows:

Cartridge entry occurs concurrently in all processors. Each processor handles a subset of the entered volumes.
Some additional processing overhead takes place, due to concurrent processing of the same list of volumes.
The cartridge entry installation exit is entered once for each volume on each processor. The installation must account for this possibility when writing the exit.

Recommendation: Use global resource serialization.

Related reading: For more information on using GRS, see z/OS MVS Planning: Global Resource Serialization.