How do i restrict a cave biome to a certain Y level?

I am currently trying to add a limestone layer similar to Deepslate, and i found an old technique which is to create a cave biome, as I want to add ores for the limestone (Which can't be done by creating limestone as a separate ore). The only problem is that i can't seem to find how to restrict the biome to a certain Y level (above y:50). Help would be appreciated.