filespec

    Name of the file in which you want SDA to log your commands
    and their output. The default filespec is SYS$DISK:[default_
    dir]filename.LOG, where SYS$DISK and [default-dir] represent
    the disk and directory specified in your last DCL command SET
    DEFAULT. If you specify SET LOG without a filename or specify SET
    NOLOG, SDA stops recording the session and directs all output to
    SYS$OUTPUT.