The DEVID keyword specifies the name of the program device that supplied the record processed in the file. The field is updated each time a record is read from a file. Also, you may move a program device name into this field to direct an output or device-specific input operation (other than a READ-by-file-name or an implicit cycle read) to a different device.
The fieldname is implicitly defined as a 10-character alphanumeric field. The device name specified in the field must be left-justified and padded with blanks. Initially, the field is blank. A blank field indicates the requester device. If the requester device is not acquired for your file, you must not use a blank field.
The DEVID field is maintained for each call to a program. If you call program B from within program A, the DEVID field for program A is not affected. Program B uses a separate DEVID field. When you return to program A, its DEVID field has the same value as it had before you called program B. If program B needs to know which devices are acquired to program A, program A must pass this information (as a parameter list) when it calls program B.
If the DEVID keyword is specified but not the MAXDEV keyword, the program assumes a multiple device file (MAXDEV with a parameter of *FILE).
To determine the name of the requester device, you may look in the appropriate area of the file information data structure (see File Information Data Structure). Or, you may process an input or output operation where the fieldname contains blanks. After the operation, the fieldname has the name of the requester device.