With release 2.1, device classes are treated solely as collections of
logical devices. This means that operations applied to a device class
are applied to all devices in a class. For example, if a spooler is
stopped for a device class, that spooler is stopped for all
logical devices in that class.
There are two reasons for device classes being treated as collections of logical devices:
Confusion. Many users have been confused by the distinction between queues and spooler processes. More confusion arose because of the different ways some of the commands operated on a logical device and the device class to which the logical device belonged.
Simplification. In earlier releases, managing separate queues for logical devices and their device classes was messy. You could never be sure when you would get a spool file or a hot device.
Before release 2.1, users could issue the following command:
and print "hot" to the printer while spool files were being created for the device classes associated with that LDEV. This is no longer possible since device classes are collections of logical devices.
There are two workarounds. If the device that you want to operate unspooled is part of a class that contains at least one other device that can remain spooled, there is no problem. The following examples assume that this other device does not presently exist.
Configure at least two devices in a particular device class. Suppose that LDEV 6 and nonexistent LDEV 19 are configured for device class LP. Make sure that the queue for LDEV 19 is open. One way to do this is to enter an OPENQ 19 command in your SYSSTART file. If LDEV 6 is usually spooled, you can also enter the STARTSPOOL 6 command or SPOOLER 6;START command in your SYSSTART file.
Make sure that your applications generating spooled output direct that output to class LP. Enter:
or
Start your application. When it is finished, enter:
or
to print the accumulated spool files.
Output directed to class LP creates spool files even while LDEV 6 is unspooled because the queue is open for at least one device (LDEV 19) in the class.
This workaround requires no dummy device. Enter:
or
Start the application requiring unspooled access to the printer. Then enter:
The first method is recommended. In the second method, there is a period of time during which any process--even one that directs its output to class LP--can acquire the printer unspooled. If it is a process other than the intended one, you must either wait for that process to close the printer, or you must abort it.
This situation does not arise with the first method because there is always at least one device in class LP with its queues open.
