Do modern operating systems use memory control blocks?

Question

I was taught in my operating systems class that sections of memory in the heap are marked as free/occupied through the use of memory control blocks (MCB). The generalized definition of an MCB that was given to us is that they hold two memory addresses (one for the next MCB and one for the previous MCB), the size of the block of memory attached to the MCB, and a flag stating whether that block is occupied or not.

When a chunk of memory is requested, the OS finds an unoccupied MCB, marks it as occupied, and creates a new MCB at the end of the now occupied block.

This seems like a sensible way to do things, and yet I cannot find any mention of the term "memory control block" outside of explanations of how DOS tracks memory allocations, even in the textbook Operating Systems Concepts (Silberschatz et al).

I'm confident that some sort of administration is going on, via a simple C++ program that creates several pointers to ints and then prints out the addresses stored by the pointers, which are consistently not consecutive (although I guess this doesn't prove anything for sure).

What's going on behind the scenes? Are MCBs simply called something else nowadays?