classes, each virtual spooling device can have only one. When a user
logs onto to the system, the class associated with a device is the one
defined in his directory entry for that device. However., he can alter
this class at any tiae by the SPOOL command. As files are created and
closed by a device, they take on the device's output class.
After they are closed and are awaiting output, their class can be
changed by a CHANGE command issued either by the file's owner or the system operator. The system operator can alter the systea generated
output class(es) of a real output device by the START co.aand. Output files transferred to a user's virtual reader can also be
controlled by class. If the receiving user has several readers, the
input to each can be liaited to files of a certain class. In addition,
the ORDER command allows sequencing of input files by class as well as
spoolid number. Output priorities can also be managed by altering the hold status of
a file. Individual users can alter the hold status with the CHARGE command, while the system operator can change (hold or free) the files
of specific individual users. SPOOL and CHANGE coamands can be used to modify the CHARS, FCB, MODIFY, and FLASH attributes of a file or a virtual printer.
These commands affect the status of a user's virtual spooling devices: SPOOL Meaning Terminates spooling operations on a specified device. It
clears the device of any pending interrupt conditions, and for
output files, updates the tag record, completes and queues the
file for real output. Optional operands allow the user to
specify a filenaae and filetype, and to override for the given
file any standard CLASS, HOLD/NOHOLD or COpy operands set into
the output device by the SPOOL command. Establishes the file attributes that apply to files created
on, or read by, the given device. It establishes the class
that will be in effect, whether: files are to be autoaatically
held, input files are to be saved or purged after reading, and
output files are to be directed to the real systea printers
and punches or are to be transferred to a user's virtual
reader. The SPOOL command also specifies 3800 attributes.
The operator can use these commands to control the activity of the real
spooling devices: Backspaces an active spooling device for either a specified nuaher of pages (printers only) or to the beginning of the
file (printers or punches).
DRAIN Stops the operation of a specified output or input device
after it has finished processing the file on which it is
currently working. A printer must be drained prior to the
issuance of the LOADBUF command. Unit record devices are
normally drained prior to system shutdown.
1-146 IBM VM/370 System Logic and Problem Deteraination--Voluae 1

START FLUSH REPEAT LOADBUF SPACE Restart a device after it has been drained. Options allow the
operator to specify the spooling output class for the output
device and output separator records. For a 3800 printer, the IMAGE CHAR, FCB and PURGE options may also be specified.
Immediately halts the output on the specified device and
either flushes that copy of the file from the system, or puts
it into the system hold status for future processing. Supplements the number of copies requested by the user for the
file when it was created. The operator can specify a number from 1 to 99 that is added to the number specified by the
user.
Loads the universal character set buffer of the FCB of the
specified printer with the specified image. If requested, the system verifies the loading by printing its contents on the
affected printer.
Forces the output on the spaced, regardless of the skipping
specified by the file's creator.
printer to be single
or spacing commands The spooling commands alter the
attributes and status of closed spool files that are queued and awaiting
processing. When a co.mand applies to an individual file, the device
type (RDR, PUN, PRT) and the spoolid number must be provided to identify
the file. In most commands requiring a spoolid, the keyword CLASS followed by a valid spool class or the keyword ALL are acceptable
substitutes for the spoolid number. This causes the command to be
executed for all files of the given class or device type. The userid is
the identification of the user issuing the command, except that the system operator must explicitly supply the identification of the user
whose files he wishes to affect or he must specify the keyword which gives access to all files (valid for CHANGE, PURGE, ORDER, and
TRANSFER commands also). CHANGE HOLD FREE PURGE ORDER Changes the filename and filetype, the number of copies, and
the class of the specified file. The CHANGE com.and also
specifies 3800 attributes. Any of the above attributes of a
file can be determined via the QUERY command. Places, via the system operator, the specified file in a hold
status. The file is not printed or punched is released by the
system operator. The operator can hold any user files by
device type.
opposite of the HOLD command. Allows a file or group of files
that were previously held to become available for processing.
However, the user cannot reset a hold that was set by the
operator with the HOLD command.
Removes unwanted spool files from the system before they printed or punched.
Reorders the input files in a virtual
order files by identification number,
combination of the two.
card reader. It can
by class, or by any TRANSFER Transfers a virtual reader to another user's virtual reader
without any processing. The TRANSFER co.mand causes a
changing in the owning userid field in the file's SFBLOK. CP Introduction 1-141