gtpi1m2jSystem Installation Support Reference

Update Tape Display

User exit routine UCCLDD issues a Load Display command to update the LED display on a tape device. UCCLDD is invoked from the exit point LDD, which is nondynamic, in one of the following routines:

General Conditions at Entry

The registers at entry to UCCLDD are:

R0
R0 must have one of the following values:

X'00'
Equated to LDDTPSW, indicates the exit was called during system error processing and came from routine CCDTPSW1 in segment CEDT.

X'04'
Equated to LDDYYY, indicates the exit was called during system error processing and came from routine LOCATEYYY in segment CEDT.
Note:
This should be taken into consideration when adding code to the exit.

R4
Pointer to the TSTB section 2 entry for the tape device in question

R6
Pointer to the TSTB section 1 entry for the tape device in question

R7
Pointer to the Load Display workarea located in the calling segment

R11-R15
See User Exit Routines - Common Entry Conditions.

System Conditions at Entry

System state
Supervisor

System mask
Masked

Protect key
0

Address space
SVM.

Programming Considerations at Entry

  1. This routine is invoked during system error processing
  2. See User Exit Routines - Common Programming Considerations for other considerations.

Programming Considerations on Return

See User Exit Routines - Common Return Conditions.

General Conditions on Return

  1. If the user exit returns condition code zero, either Message 1, Message 2, or both messages will be displayed.
  2. If the exit returns a non-zero condition code, no message will be displayed.