This section covers how to define data sets for use with PL/I files that have the STREAM attribute. It covers the ENVIRONMENT options you can use and how to create and access data sets. The essential parameters of the DD statements you use in creating and accessing these data sets are summarized in tables, and several examples of PL/I programs are included to illustrate the text.
Data sets with the STREAM attribute are processed by stream-oriented data transmission, which allows your PL/I program to ignore block and record boundaries and treat a data set as a continuous stream of data values in character or graphic form.
You create and access data sets for stream-oriented data transmission using the list-, data-, and edit-directed input and output statements described in the PL/I Language Reference.
For output, PL/I converts the data items from program variables into character form if necessary, and builds the stream of characters or graphics into records for transmission to the data set.
For input, PL/I takes records from the data set and separates them into the data items requested by your program, converting them into the appropriate form for assignment to program variables.
You can use stream-oriented data transmission to read or write graphic data. There are terminals, printers, and data-entry devices that, with the appropriate programming support, can display, print, and enter graphics. You must be sure that your data is in a format acceptable for the intended device, or for a print utility program.