(also does this genre have a name so I can search it)
The kink is called macrophilia (love of giants).
I think microphilia is more accurate. Macrophilia entails huge people with genitals the size of buildings. I know it's really pedantic, but micro and macro are really two separate sort of sexual fantasies.
Macrophilia is probably the better term as it is more widely used. After all, there are two sides to the encounter – their size difference is what makes the fetish. Call the smaller guy a macrophile, the larger a microphile. Rather than clutter everything up with a multitude of definitions, I'm satisfied to label everything macrophilia.