As described inFunctions of the SAP Memory Management System, there are various kinds of memory (SAP Memory Types).
The memory management system decides when and what type of memory gets allocated and the limit at which a different memory type is allocated.
This all depends on the platform and the work process type (dialog or non-dialog work processes). The allocation of memory for UNIX platforms is described in more detail underAllocating Memory for User Contexts.
Under AIX, you can also use a different method to implement the extended memory. This means that more extended memory is available for an individual context. The procedure and the benefits thereof are described in more detail underConfiguration for AIX.
See also:Allocating Memory for User ContextsImplementing the Extended Memory Under UNIX