To clear the screen from DCL use one of the following methods:

$ CLS:==TYPE/PAGE NLA0:
$ CLS

or:

$ CLS:==@disk:[dir]CLS.COM
$ CLS

where CLS.COM contains:

$ CSI[0,8]=155
$ WRITE SYS$OUTPUT "''CSI'2J"

The method:

$ CLS:==SET TERMINAL/WIDTH=80
$ CLS

is not so good, because:
  - actual terminal width is difficult to determine
    (the width VMS thinks it has is easy to get, but
    that may not be the same)
  - some third party VT clones do not support this