Library /sys$common/syshlp/macro$dwci.hlb options, listing, list  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Click on the Produce a Listing File button to direct
  the assembler to produce a listing of the source file.
  By default, the listing file is given the name of the
  source file plus the .LIS extension.  You can
  optionally change the file name to any valid name of
  your choice.

  If you are assembling multiple files and you type in a
  file name, each listing file is given that name (with
  an incremental version number).

  Equivalent qualifier (DCL interface):

     /[NO]LIST[=file-spec]