Teraservices are the opposite of microservices. The teraservices design entails a sort of a monolithic service. Teraservices require two terabytes of memory, or more. These services could be used when services are required only to be in memory and have high usage.

These services are quite costly in cloud environments due to the memory needed, but the extra cost can be offset by changing from quad-core servers to dual-core servers.

Such a design is not popular.

https://dzone.com/articles/microservices-nanoservices-teraservices-and-server-1