$B PRT(nnnnn) and $B R(nnnnn).PR(m)

Function

To backspace printer output a specified number of pages, to the beginning of a data set, or to the most recent checkpoint.

Syntax


>>-$B--+-PRTnnnnn---+--+------+--+--------------------+--------->
       '-Rnnnnn.PRm-'  '-,--D-'  '-,--C--+----------+-'   
                                         '-,--pages-'     

>--+----------+------------------------------------------------><
   '-,--pages-'

Parameters

nnnnn

For PRT, the identifier of the local printer (1-32767) to backspace output on. For R, the identifier of the remote workstation (1-32767) that is attached to printer m (1-7).

m

The identifier of the printer (1-7) that is attached to the remote workstation Rnnnnn (1-32767).

C

Output is backspaced to the most recent checkpoint. JES2 assumes that all data up to the most recent checkpoint has printed successfully. Backspacing to the most recent checkpoint is the only way JES2 can ensure no loss of data for remote printers.

You can also specify pages with C, which causes JES2 to backspace the data set pages further than the most recent checkpoint.

D

Output is backspaced to the beginning of the data set. Printing resumes at the beginning of the data set.

pages

Specifies the number of pages, or for FSS printers, the number of sides, that the output is to be backspaced. For FSS devices, this can be up to 8 digits in length (1-99999999). For other devices, it can be up to 4 digits in length (1-9999).

If you are using an impact printer and you specify pages for data sets with a line count of zero and no channel skips, JES2 backspaces the output to the beginning of the data set. This happens regardless of the value specified for pages (The line count for a data set is specified by the LINECT parameter on the PRINTDEF initialization statement or the LINECT parameter on the /*JOBPARM JES2 control statement, /*OUTPUT JES2 statement, in the JOB statement accounting field, or on the OUTPUT JCL statement.)

For the 3800 printer running in JES mode, specifying 1-9999 causes backspacing of the output for the specified number of physical pages.

For FSS mode devices, specifying 1-99999999 causes backspacing of the output for the specified number of sides. When simplex printing, there is one side per sheet of paper. When duplex printing, there are two sides per sheet of paper.

Each page in a copy group (a collection of contiguous pages representing multiple copies of a data set to be printed) is counted as a separate page. You can backspace all the way to the beginning of the data that is currently being stacked. Because multiple jobs can be active concurrently on the 3800, the backspace could require crossing data set or job boundaries.

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, SA32-0991.

Processing Considerations

If you omit D, C, and nnnnn, one page is the default backspace.
For data sets with no channel skips and a line count of zero, you specify the number of lines in a page by either:
- The CKPTLNS parameter on the /*OUTPUT JES2 statement.
- The CKPTLINE parameter on the PRTnnnnn and Rnnnnn.PRm initialization statements, the OUTPUT JCL statement, or using the $T device command.
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 PRTnnnnn and Rnnnnn.PRm initialization statements, the OUTPUT JCL statement, or using the $T device command.
Restarted output that is selected by an FSS printer controlled by PSF cannot be backspaced beyond the point of interruption.
For the 3800 printer, the backspacing is relative to the page that is visible at the transfer station.
The $B command is useful if a printer jam causes one line to be overprinted multiple times. After you clear the jam, you can backspace to a point in the data set before the printer jam and resume printing.
For impact printers, the number of pages to backspace is affected by channel skips. JES2 counts all channel skips as new pages.
Note: The printer must be physically stopped before entering a backspace command for that printer in order to maintain proper line count displays through $DU,PRTx.

Scope

Single member. The values supplied for this command will be in effect for this member only. There is no need to have this command issued to all members of the MAS.

Messages

The $HASP170 message displays the status of output processing on the specified printer.

Examples

 1   $b r9.pr1,c

  $HASP170  R9.PR1 BACKSPACED

JES2 backspaces the output on printer 1 of remote 9 to the most recent checkpoint. If no checkpoint exists, or if the page currently being printed precedes the most recent checkpoint (this can happen if the data set was previously repositioned behind the most recent checkpoint by another $B command), JES2 backspaces the output to the beginning of the data set. For example, if the most recent checkpoint was taken at the top of page 145 but the printer is currently printing page 141, JES2 will backspace the output to the beginning of the data set.

 2   $b r11.pr1,c,10

  $HASP170 R11.PR1 BACKSPACED

JES2 backspaces the output on printer 1 of remote 11 ten pages behind the most recent checkpoint. If no checkpoint exists, or if the page currently being printed precedes the most recent checkpoint, JES2 backspaces the output to the beginning of the data set.