Is mindfulness itself kamma ? does it create kamma?

Is mindfulness itself kamma ? does it create kamma ? is it one of the 50 types of kamma ? (my teacher who is a monk told me mindfulness is kamma - and like kamma its an accumulated thing ) Im asking cause if mindfulness is kamma than its accumlated - and if its accumlated it answers my "problem" : https://buddhism.stackexchange.com/questions/18641/is-there-a-value-for-a-single-moment-of-mindfulness-without-others