Allocating an I/O Device to JES3

To allocate an I/O device that JES3 needs during initialization, include a DD statement for the device in the JES3 start procedure. To dynamically allocate the device, omit the DD statement and include a DYNALLOC statement for the device in the JES3 initialization stream. Before you dynamically allocate a device, however, there are two restrictions you should be aware of:

• You cannot specify unit affinity for a dynamically allocated device.
• You cannot use the ddname of a dynamically allocated device to assign unit affinity to a device defined in the JES3 start procedure.