$B PUN(nn) and $B R(nnnnn).PU(m) - Logically backspace punch output
Function
To backspace punch output a specified number of cards, to the beginning of a data set, or to the most recent checkpoint.
Syntax
Parameters
- nn
- The identifier of the local punch (1-99) on which JES2 backspaces output.
- nnnn
- The output is backspaced nnnn (1-9999) cards.
- nnnnn
- The identifier of the remote workstation R (1-32767) that is attached to punch m (1-7).
- m
- The identifier of the punch (1-7) that is attached to the remote workstation Rnnnnn (1-32767).
- C
- The
output is backspaced to the most recent checkpoint. JES2 assumes
that all data up to the most recent checkpoint has punched successfully.
Backspacing to the most recent checkpoint is the only way JES2 can
ensure no loss of data for remote punches.
You can also specify nnnn with C, which causes JES2 to backspace the output nnnn cards further than the most recent checkpoint.
- D
- The output is backspaced to the beginning of the data set. Punching resumes at the beginning of the data set.
Authority Required
This command requires device authority. The description of the $T RDRnn command explains how to ensure that the authority of the appropriate MVS™ system command group is assigned.
This command requires update security access authority. For a description of assigning command input authority, see z/OS JES2 Initialization and Tuning Guide.
Processing Considerations
- If you omit D, C, and nnnn, one card is the default backspace.
- The amount of output between checkpoints is controlled by either:
- The CKPTLNS and CKPTPGS parameters on the /*OUTPUT JES2 statement.
- The CKPTLINE and CKPTPAGE parameters on the PRTnn and Rnn.PRm initialization statements, the OUTPUT JCL statement, or using the $T device command.
- The $B command is useful if a punch jam causes a loss of punched cards. After you clear the jam, you can backspace to a point in the data set before the punch jam and resume punching.
Scope
Single member. The values supplied for this command is in effect for this member only. There is no need to have this command that is issued to all members of the MAS.
Messages
The $HASP170 message displays the status of output processing on the specified punch.
Examples
1 $b r9.pu1,c
$HASP170 R9.PU1 BACKSPACED
2 $b r11.pu1,c,10
$HASP170 R11.PU1 BACKSPACED
JES2 backspaces the output on punch 1 of remote 11 ten cards behind the most recent checkpoint. If there is no checkpoint, or if the card currently being punched precedes the most recent checkpoint, JES2 backspaces the output to the beginning of the data set.