/WORK[=work-file] (default)
  /NOWORK

  Determines the work file, if any, that DECTPU uses to swap memory for
  editing very large files.  The work file is automatically deleted
  when you exit.  If you invoke DECTPU and disable the /WORK qualifier,
  DECTPU does not have a work file.  In this case, the amount of memory
  available to DECTPU limits the size of the files you can edit.

  You cannot use wildcards to specify the work file.  There is one work
  file per editing session.  Default file type is .TPU$WORK.

  By default, DECTPU creates a work file named TPU$WORK.TPU$WORK in
  SYS$SCRATCH, which is usually your top-level, login directory.  There
  are two ways to specify a different work file:

  o  Define the TPU$WORK logical name to specify the work file.

     This is useful if you want the work file created in an area other
     than SYS$SCRATCH, such as on a larger disk.  You can put the
     definition in your LOGIN.COM file.

  o  Use /WORK= and specify the work file you want created.

     This overrides any definition of the TPU$WORK logical name.  For
     example, the following command invokes DECTPU, specifying the work
     file to be MYWORK.TPU$WORK:

        $ EDIT/TPU /WORK=mywork

  To create the work file in an area other than SYS$SCRATCH, specify
  the device (disk) and directory of the work file.

  If you not want DECTPU to create a workfile, use /NOWORK.  This
  reduces consumption of system resources and makes startup faster.
  Generally, you can use /NOWORK unless your system has limited memory
  or unless you edit very large files or large numbers of files.