To avoid the possibility of another
user mounting a particular device before you enter the MOUNT command,
you can optionally allocate the device before issuing the MOUNT command.
Use the DCL command ALLOCATE to provide your process with exclusive
access to a physical device until you either deallocate the device
or terminate your process. Optionally, you can associate a logical
name with the device. The format for the ALLOCATE command is as follows:
ALLOCATE device-name[:] logical-name[:]