Parent topic: Job logs
A spooled file holds output data until it can be printed. The spooled file collects data from a device until a program or device is able to process the data. A program uses a spooled file as if it were reading from or writing to an actual device. This is input and output spooling.
Input spooling is done by the system for database and diskette files. An IBM-supplied program, called a reader, is started in the spooling subsystem, reads the batch job streams from the device, and places the jobs on a job queue.
Output spooling is done for printers. An IBM-supplied program, called a printer writer, is started in the spooling subsystem, selects spooled files from its output queue, and writes the records of the spooled output file to the printer.
At the end of a the job, the job log can be written to the spooled file QPJOBLOG so that it can be printed.
