⎕NRESIZE Alter the size of a native file

The ⎕NRESIZE function can be used to reserve space on disk for a file. The file must have been opened in a mode which permits writing. The syntax of ⎕NRESIZE is :

          SIZE ⎕NRESIZE TIENO

TIENO is the tie number of file to resize

SIZE specifies the new size for the file in bytes

If the new size is larger than the current size of the specified file, the file is extended to the new size by writing bytes of zeros.