The VMS System Generation Utility (SYSGEN) allows  you  to  tailor
  your system for a specific hardware  and  software  configuration.
  Use SYSGEN to modify system parameters, load device  drivers,  and
  create additional page and swap files.

  More on-line help is available from the  System Generation Utility.
  To invoke  SYSGEN,  enter the following command in response to the
  DCL prompt:

  $  RUN SYS$SYSTEM:SYSGEN

  The utility responds with the prompt:

  SYSGEN>

  After you invoke SYSGEN, you can enter HELP or any of the  SYSGEN
  commands.