Extended memory
Extended memory is the core of the memory management system. Each work process has a part reserved in its virtual address space for extended memory.
More information: Virtual Address Space of a Work Process
You can set the size of extended memory using the profile parameter em/initial_size_MB: Extended Memory Pool Size. Under Windows, further memory is assigned dynamically as needed, and you can also set this amount.
The SAP system builds a layer on to the operating system functions for the page management of this memory. The extended memory is implemented as an unnamed mapped file. This means the virtual address space uses the swap space of the operating system as background memory.
Address Stability
You can map the extended memory from the extended memory pool onto any work process, and after onto another process (see graphic) on the same address in the virtual address space. This is important if you work with pointers in the ABAP program.
Operating System Dependencies
Depending on the operating system, how you implement the extended memory is different. Platform-Specific Description of Memory Management