How to check who’s allocating a device unit

Let’s say for instance that you have a DASD volume (TSTCT1) and you would like to know who’s using it (allocating it).

In order to do this we first need to know the unit address of said device:

/D U,VOL=volume_name

In our example:

/D U,VOL=TSTCT1

Result:

RESPONSE=TST1
IEE457I 09.53.10 UNIT STATUS 444
UNIT TYPE STATUS        VOLSER     VOLSTATE
7001 3390 A             TSTCT1     PRIV/RSDNT

Note: In this case as we can see the unit address of TSTCT1 is 7001.

Once we know the unit address then we can check who’s allocating it by using the command:

/D U,,ALLOC,address,1

In our case:

/D U,,ALLOC,7001,1

Result:

RESPONSE=TST1
IEE106I 09.56.08 UNITS ALLOCATED 623
UNIT    JOBNAME  ASID   JOBNAME  ASID   JOBNAME  ASID   JOBNAME  ASID
7001 *MASTER* 0000   *MASTER* 0001   XCFAS    0006   OMVS     000E
7001 CATALOG  0023   LLA      0024   JES2     0028

Note:

We use “1” in the end of the command so that we only get the display for the single device we’ve specified in the command.