How does an SAP Work Process access memory?

An SAP process accesses memory in the following way:
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• In dialog processes (Process type DIA)
1. The first section of the roll area up to parameter ztta/roll_first - then -
2. Extended memory up to parameter ztta/roll_extension -or- extended memory (size: em/initial_size_MB) is exhausted - then -
3. The rest of the roll area (size: ztta/roll_area) - then -
4. Process local memory up to parameter abap/heap_area_dia -or- operating system swap space is exhausted -or- the process's data segment size is exceeded -or- the process's address space is exceeded -or- the operating system's address space is exceeded.

NOTE: Under Windows NT the allocation sequence of non-dialog work processes is the same as with a dialog work process.

• In non-dialog Processes (Process type VB, UP, BTC)
1. The total roll area (size: ztta/roll_area) - then -
2. Process local memory up to parameter abap/heap_area_nondia -or- operating system swap space is exhausted -or- the process's data segment size is exceeded -or- the process's address space is exceeded -or- the operating system's address space is exceeded. - then -
3. Extended memory up to parameter ztta/roll_extension -or- extended memory (size: em/initial_size_MB) is exhausted.