what are they used for though in chan and zen buddhism? mostly what i found searching on line is just people saying that mainly chan and zen don't use them and that when they do it's only a small number of people in sects that have been influenced by vajrayana or pure land. but i see pictures everywhere of chan and zen monks and famous masters wearing or holding malas (modern in photographs and ancient in drawings, paintings and statues) so it seems a little more wide spread than just a few sects or monks influenced by vajrayana or pure land. i can't find anywhere that the practice is explained. all the zen/chan writings i have come accross detail morality, koans, mindfulness, sitting meditation, etc. but i have never come across any that detail or recommend mala practice. i'm puzzled.
could someone tell me how precisely they are used in zen/chan and what specifically is chanted. as much detail as possible please

