SPOOLING FUNCTIONS CP spooling support performs the following five functions for virtual
aachines:
1. It siaulates, with software routines, the operation of the virtual
unit record devices that are attached to each user's virtual
machine. The simulation makes it appear that the program in the
virtual machine controls real unit record devices. Unit record
device simulation involves the interception and interpretation of
user Start I/O (SIO) instructions, the movement of data to and from the user's virtual storage space, and the reflection of
interruption codes and ending conditions in the virtual machine.
2. It operates the real unit record equipment attached to the real machine. Spooling moves print-image and punch-card-image files to
a real printer and card punch, and creates spool files froa data
read in fro. the real card reader.
3. It provides an easy-to-use interface between the machine users, the system operator, and the spooling system to allow
flexible and easy switching of system resources between many users. A set of general user and operator commands can request these
functions.
4. It allows keyed-in CP machine console input
or in addition to,
initiate or terminate
terminal session. commands and responses as well as virtual
and output to be placed on disk instead of,
being displayed at the terminal. You can
virtual console spooling at any time during a
5. It provides the ability telefrccessing network.
to spool files across the RSCS Spooling commands can be separated by type into those that affect
virtual devices, those that affect real devices, and those that affect
queued spool files within the system. The commands that affect virtual
devices are available to all general users; a user may affect the status
of devices that attach to only his virtual machine. For a discussion of
the Class G spooling commands, see VBL.Jl.Q £R £2!.!s!lg Only the spooling or resource operator can use commands that affect
the status of the real spooling devices. Commands affecting the user's
virtual machine closed spool files that are awaiting processing are
available to all users, with some additional capabilities available to
the spooling operator. For eXaaFle, a user can alter characteristics of
only those files that have the same userid as his, but the spooling
operator can change the status of any spool file in the system. The "CP Commands" section of this publication describes these commands. You can create input spool files (that is, data available at a
specific user's virtual card reader), when you flace cards in the real card reader that are preceded by a special V!/370 card that identifies the virtual machine userid of the user requesting spool files. When the virtual machine operating system writes to a virtual printer
or card punch, it output spool files and stores thea on direct
access devices. Real output is scheduled for a real printer or card
punch, or for reaote output, whenever a user logs off the system or
issues a CP spooling co.mand to close the file. 210 VB/370 Operator's Guide

You can transfer specific files from the spooled printer or card
punch of a virtual machine to the card reader of the saae or another
virtual machine. (I virtual card reader is not li.ited to records.) Files are not physically printed or punched when transferred
between virtual unit record devices by the spooling routines. With this
method, you can make files available to multiple virtual machines, or to
different operating syste.s executing at different times in the saae
virtual machine.
The Remote Spooling Communicatioris subsystem,· with the CP spooling
system, provides support for spooling across a teleprocessing network.
For detailed information about RSCS, see the !!L370 Guide. V!/370 spooling includes many options for the virtual machine user
and the real machine operator. These include aultiple copies
of a single spool file, backspacing any nuaber of printer pages, and
defining or reordering spooling classes for real output Real, printers with the Universal Character Set feature must have the
block data check set when using V!/370 spooling. The LOIDBUF comaand automatically sets the block data check. For more details on spooling,
see "Spooling Considerations."
The terminal user can spool virtual console output and virtual
input keyed in by him in addition to typing or displaying it
terminal. Furthermore, if the virtual console is disconnected
virtual machine is active, the console spool file acquires all
output that would normally print or display at the terminal.
console I/O consists of all initiated CP commands and responses,
as the communication to and from the operating system running
virtual machine. You start virtual console spooling when you issue the command: SPOOL CORSOLE START console
at the
and the
console
virtual
as well
in the You close the console spool file at logoff time or when you stop and
close the file. When you close the console spool file, it goes on the
printer spool file and then the operator can manipulate it in the same way as any other printer spool· file.
The display output of local or remote 3270s in DISPLAY mode (every 16
lines) is written automatically on the spool file if the operator is the system operator and the device was specified as a graphic device
supported as a virtual machine operator's console.
Console spooling for the system operator continues even if the
operator disconnects fro. one terainal and logs onto another. To stop
the automatic console spooling, the operator must issue the SPOOL CONSOLE STOP comaand. If the system fails, up to 16 lines of output may be lost from the system operator's spool file, but the system closes the
console spool file when the failure occurs. However, virtual machine operators may lose up to one page of spooling data in a system failure
because their spooling buffer is one page (4096 bytes) in size.
In regard to DISD I/O, errors occurring on sFool and paging devices
produce error messages that appear on the system operator's ter.inal. Section 5. operator Spooling Functions 211