A managed memory in which multiple computing entities each have a corresponding entity-specific portion that is subject to garbage collection. An immutable buffer is located outside of managed memory. For a given computing entity, the corresponding managed memory portion contains entity-specific objects that can be accessed by a specific computing entity, but not by the other multiple computing entities. For one or more of the entity-specific managed memory portions, the portion also includes a reference to shared memory, such as an immutable buffer. The reference is structured to be ignored by the garbage collector, though the reference may appear just as a normal object in the managed memory portion. Thus, a unified memory access model is made possible in which the methods for a computing entity to access a regular object in managed memory is similar to how the computing entity accesses shared memory.