The format of the MSGDISP macro with the DEMOUNT parameter is:

>>-+-------+--MSGDISP--DEMOUNT--,UCB=-(reg)--------------------->
   '-label-'                                  

>--+-----------------+--+-------------------+------------------->
   |        .-'D'--. |  '-,MF=-+-L--------+-'   
   '-,DISP=-+-'K'--+-'         '-(E,addr)-'     
            +-'R'--+                            
            '-addr-'                            

>--+-------------------+--+------------------------------+------>
   |          .-'S'--. |  '-,MSER=-+-'volser_to_mount'-+-'   
   '-,MLABEL=-+-'A'--+-'           '-addr--------------'     
              +-'N'--+                                       
              +-'X'--+                                       
              '-addr-'                                       

>--+--------------------+--+--------------+--------------------->
   '-,SER=-+-'volser'-+-'  '-,MEDIATYPE=n-'   
           '-addr-----'                       

>--+-----------------+--+----------------+---------------------->
   |         .-YES-. |  |        .-NO--. |   
   '-,INDEX=-+-NO--+-'  '-,TEST=-+-YES-+-'   

>--+----------------+------------------------------------------><
   |        .-YES-. |   
   '-,WAIT=-+-NO--+-'   

DEMOUNT

Displays a volume disposition indicator in position 1 until the volume is demounted. Optionally, you can display the serial number of the volume to be demounted at the same time. The display flashes on and off. If a volume is not mounted on the device when the display request is executed, blanks are displayed.

The demount message can be displayed alternately (flashing) with a mount message for the next volume by specifying the MSER parameter.

UCB=(reg)—(2-12)

Specifies a register containing the UCB address for the device. Use the address of a UCB, not a UCB copy.

DISP='D' or 'K' or 'R' or addr

Specifies the character to display in position 1 of the pod, representing the volume disposition.

'D'

Specifies demount a public volume. Apostrophes are required. "D" also displays when you specify an invalid character or when the volume use attribute is unknown (as in an automatic volume recognition (AVR) error when reading a label).

'K'

Specifies keep a private volume and return it to the library. Apostrophes are required.

'R'

Specifies retain a private volume near the device for further use. Apostrophes are required.

addr—RX-type address, A-type address, or (2-12)

Specifies the address of an area containing a “D”, “K”, or “R”. For MF=L, you can only specify an A-type address.

MF=L or (E,addr)

Specifies either the execute or list form of MSGDISP. If you do not specify this parameter, the standard form of the macro is used.

L

Specifies the list form of MSGDISP. This generates a parameter list that can be used as input to the execute form. The execute form can modify the parameter list.

(E,addr)

Specifies that the execute form of the macro and an existing parameter list is to be used.

addr—RX-type address, (1), or (2-12)

Specifies the address of the parameter list.

MLABEL='A' or 'N' or 'S' or 'X' or addr

Displays the label type of the volume to be loaded and made ready following a demount, in position 8. If you specify an unknown label type other than a blank, a "?" is displayed. You can only specify this parameter if you also specify the MSER parameter.

'A'

Specifies ISO/ANSI (AL) or ISO/ANSI with user (AUL) labels. Apostrophes are required.

'N'

Specifies no labels (NL), LTM (leading tape mark, created by VSE), or bypass label processing (BLP). Apostrophes are required.

'S'

Specifies IBM® Standard (SL) or IBM Standard with user (SUL) labels. Apostrophes are required.

'X'

Specifies nonstandard (NSL) labels. Apostrophes are required.

addr—RX-type address, A-type address, or (2-12)

Specifies the address of an area containing an “A”, “N”, “S”, or “X” (see the following explanations of these characters). For MF=L, you can only specify an A-type address.

MSER='volser-to-mount' or addr

Displays the mount message for the next volume alternately (flashing) with the demount message. The display continues until you demount the current volume. At that time, the mount message will display (flashing) until you load the volume and make the device ready. If no volume is mounted at the time the demount and mount messages are executed, only the mount message will display (flashing) until the volume is loaded and ready.

'volser-to-mount'

Specifies the volume serial number of the volume to be mounted, as a literal. Apostrophes are required.

addr—RX-type address, A-type address, or (2-12)

Specifies the address of the volume serial number of the volume to be mounted. For MF=L, you can only specify an A-type address.

SER='volser' or addr

Specifies the serial number of the volume to be demounted. The serial number is displayed in positions 2 through 7. If you do not specify SER, the system supplies the volume serial number. If the serial number is not available, a scratch volume is used, unless the volume use attribute indicates a default of “PRIVAT”.

'volser'

Specifies the volume serial number as a literal. Specify with apostrophes.

addr—RX-type address, A-type address, or (2-12)

Specifies the address of the volume serial number. This parameter is not valid for the MF=L form. For MF=L, you can only specify an A-type address.

MEDIATYPE=n

Specifies what media type to demount for SCRTCH or PRIVAT demounts. The MEDIATYPE keyword applies only when volumes are to be demounted on devices that reside in a Manual Tape Library (MTL). If MEDIATYPE is specified for devices outside of a Manual Tape Library, it is ignored. The value n can be specified as a literal, the address of a 1 byte field containing the value, or the name of the addressable field containing the value. Valid values for MEDIATYPE are the numbers 1 through 8.

INDEX=NO or YES

Specifies whether the ACL should be indexed to satisfy a scratch mount request.

NO

Specifies that indexing should not be done regardless of the state of the ACL.

YES

Specifies that indexing should be done if:

• The ACL is present and loaded, and
• The request is for SCRTCH or PRIVAT.

TEST=NO or YES

Specifies whether the macro expansion is to include code that tests the UCB to determine whether message display is supported. If the result of the test is that the message display is not supported, an SVC is not invoked.

NO

Specifies that the macro expansion is not to include code that tests the UCB to determine whether the device supports message display.

YES

Specifies testing the UCB by the MSGDISP macro before attempting to invoke the message display service routine.

Requirement: TEST=YES requires you to include the UCB mapping macro (IEFUCBOB) in the source code. If this provision is not followed, a program check in expansion code might result. Programs running in AMODE 24 and invoking the MSGDISP macro with the TEST=YES parameter cannot pass the actual address of a UCB that resides above the 16 MB line. These programs must pass the captured UCB address or, if an actual address is passed, the UCB must reside below the 16 MB line.

WAIT=NO or YES

Specifies when control is to be returned to you.

NO

Specifies that the MSGDISP function is not to wait for completion of I/O initiated on the caller's behalf. When MSGDISP returns, the I/O request might still be running. I/O return codes are not returned, and I/O errors are recorded in the same manner as any permanent error by the error recovery procedure.

YES

Specifies that control is to be returned after I/O is complete.