3.2.4 Linker Output Files
  When you enter the LINK command interactively and do not
  specify any qualifiers, the linker creates only an executable
  image file. By default, the resulting image file has the same
  file name as the first object module specified, and the file type
  .EXE.

  In a batch job, the linker creates both an executable image
  file and a storage map file by default. The default file type for
  map files is .MAP.

  To specify an alternative name for a map file or image file, or
  to specify an alternative output directory or device, you can
  include a file specification on the /MAP or /EXECUTABLE
  qualifier. For example:
  $ LINK UPDATE/MAP=TEST