Syntax:

      /KEEP = number

  Use /KEEP to specify how many history list entries you want to  save.
  DMU  then deletes all but that number of the most recent history list
  entries.

  You cannot specify both /BEFORE and /KEEP in the same  command  line.
  If you do not specify either /BEFORE or /KEEP, the default is /KEEP =
  0, and all history list entries are deleted.