// H E A P . DF structure ZONE: [ free word; ovh word; min word; max word; cfree word; dummy word; ]; structure HP: [ siz word; fp word; [ bp word; ] = [ use word; ] ]; manifest [ hpovhf = 4; zonel = 5+hpovhf; prevfree = 1; bsiz = 1; minlink = #400; ];