Usage: SET HISTORY_FILE <path for history file>
  If HISTORY_FILE is set, then the command history is saved in
  this file rather than in memory.  The advantage to this is
  that the size of this file is limited by your disk space and
  doesn't increase the memory usage of IRCII.  The disadvantage
  is that history access might be slower (or it might not).  To
  disable the HISTORY_FILE, set it to <EMPTY>.  To completely
  disable the command history functions, you must also set
  HISTORY to 0.