What is the maximum amount of memory (heap) that can be used within a single application?

In a single C# application, usually one memory space managed by the garbage collector is used — one heap. However, depending on the runtime implementation (for example, .NET CLR), the heap can be divided into several segments for optimization:

• Managed Heap — the main heap for managed objects.
• Large Object Heap (LOH) — a separate segment for large objects.
• Pinned Object Heap (POH) — for objects with fixed memory locations (in newer versions of .NET).

Despite these segments, from the application's perspective, it is one logical heap. Thus, it can be said that the application uses one managed heap, which can be internally divided into several areas for optimization.

If we talk about unmanaged memory, the application can allocate memory in different areas (for example, through native API calls), but this is outside the context of the managed .NET heap.