The system spooler interface program opens a system spooler file for either input or output, reads or writes a file, and closes a file. These functions are for system programmer use. The input is single-threaded, so only one transaction can use it at a time.
An application can send files to a remote location by specifying the node of the location, and the userid (or external writer name) of the user at that location. To retrieve a file at the remote location, you specify the external writer name, and you can then retrieve reports from that writer. For security reasons, the external writer name must begin with the same four characters as the CICS® applid. The remote system to which a file or report is sent, or from which it is received, must have JES under MVS™, or VM.
The SPOOLOPEN command dynamically allocates input or output files using the CICS SVC, and an application control block (ACB) is opened to process the file. For an input file, the IEFSSREQ macro is also issued to determine which file to process. The SPOOLREAD or SPOOLWRITE commands cause GETs or PUTs to be issued using the ACB. The SPOOLCLOSE command dynamically deallocates a file, and causes it to be either transmitted or deleted. All processing which could cause CICS to be suspended is performed under an operating system subtask which is initiated by subtask control, DFHSKP.
DFHPSPST runs under CICS, but DFHPSPSS, and modules called as a result, run under the subtask.
When a system spooler interface command is executed, the normal sequence of invocation of modules is:
DFHPSP is called by:
If a user transaction terminates without issuing a SPOOLCLOSE command, DFHPSPDW is invoked to process a DWE that was set up when the SPOOLOPEN command was processed. This closes the file in the usual way.
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