This section covers how to define data sets for use with PL/I files that have the STREAM attribute. The essential parameters you use in the DD:ddname environment variable for creating and accessing these data sets are summarized, and several examples of PL/I programs are included.
Data sets with the STREAM attribute are processed by stream-oriented data transmission, which allows your PL/I program to ignore record boundaries and to treat a data set as a continuous stream of data values. Data values are either in character format or graphic format—that is, in DBCS (double byte character set) 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 format if necessary, and builds the stream of characters or DBCS characters 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 DBCS data (graphics). DBCS data can be entered, displayed and printed if the appropriate devices have DBCS support. You must be sure that your data is in a format acceptable for the intended device or for a print utility program.