The following attributes are appropriate for use with stream files. Some may be used in either the DECLARE statement for the file constant or in the OPEN statement, others only in the OPEN statement.
| Attribute | Permitted in Specification |
|---|---|
| STREAM | DECLARE or OPEN |
| INPUT | DECLARE or OPEN |
| OUTPUT | DECLARE or OPEN |
| DECLARE or OPEN | |
| LINESIZE | OPEN |
| PAGESIZE | OPEN |
| TITLE | OPEN |
The use of PRINT implies STREAM OUTPUT. If neither INPUT, OUTPUT, nor PRINT is specified, INPUT is assumed. LINESIZE and PAGESIZE can be used only for PRINT files. If neither STREAM nor RECORD is specified, the default is STREAM. (See the section Record I/O.) STREAM and RECORD are mutually exclusive, as are INPUT and OUTPUT. If attributes are specified both in the DECLARE statement and the OPEN statement for a file, the attributes used are the combination of those in the two statements. The combination may include only one of each mutually exclusive set.
The TITLE option is used to associate a file as declared in the PL/I program with a file or device as known to the operating system. In the following examples of OPEN statements, the quoted text in the TITLE options specifies the system filename or device name to be used in I/O operations with the opening of the PL/I file indicated by the FILE option. If the TITLE option is not specified in an OPEN statement, the declared name of the file constant is used as the default title.
The LINESIZE option is used in an OPEN statement to specify the maximum number of characters that can be output in a single line for a STREAM file. If no line size is specified, a default line size is assumed. For more information on LINESIZE, see the section PUT in the chapter Statements.
The LINESIZE option can appear in the OPEN statement only and is valid only with STREAM OUTPUT files. During output, a newline will be inserted whenever the column position equals (LINESIZE+1). The SKIP or LINE options with a PUT statement cause a newline character to be inserted and the column position to be reset. The COLUMN format with a PUT EDIT statement may cause a newline to be inserted.
The default may vary according to the file name or device. In Open PL/I, the default value of the LINESIZE option is 120.
The PAGESIZE option is used in an OPEN statement to specify the maximum number of lines that can be written to a print file without signaling the ENDPAGE condition. If no page size is specified, a default page size is supplied. In Open PL/I, the default value of the PAGESIZE option is 60.
If a GET or PUT statement is executed on a file that has not been opened, the file is implicitly opened as a STREAM file using the declared name of the file constant as the title. A file so opened by a GET statement is opened as an INPUT file, one so opened by a PUT statement is opened as an OUTPUT file.
You can add text to any existing stream file (any ASCII file) by using the -APPEND option in the TITLE option of the OPEN statement. Thus, if the file you wish to append to is named "logfile," open it with the following TITLE option:
TITLE('logfile -APPEND')
Any subsequent PUT statements to this file simply append their output to the end of the file.