SAP Memory Management

a. Whenever user session is allocated , dialog work process normally allocates Extended Memory (EM) and once quota of EM is exhausted then its allocates PRIV memory (HEAP).

b. Where as in case of non-dialog work process PRIV memory (HEAP) has been allocated first and then EM.

c. Memory management in SAP is a mechanism to restrict the individual session from consuming whole system memory

Extended memory :

1. Dialog Work Process

• Due to frequent content switch is happening , which is possible is EM only.
• EM will be available for dialog till maximum allocated memory is exhausted
• Limit can be set with parameter ztta/roll_extension_dia

     2. Non-dialog Work process

• Once PRIV memory is exhausted , EM will allocated.
• If EM is also exhausted for the non-dialog work process, then ABAP dump will be created.
• Limit can be set with parameter ztta/roll_extension_nondia.

Heap Memory:

      1. Dialog Work process 

• It can only be allocated once EM memory quota is exhausted.
• ABAP dump will be generated once PRIV memory area has been exhausted.
• Limit can be set with parameter abap/heap_area_dia

      2. Non- dialog Work Process

• No frequent context switching happens .
• Heap memory is a local memory assigned for the Work process in SAP.
• Quota can be defined with parameter  abap/heap_area_nondia.

Exception:

If  EM or PRIV memory has been reached to its assigned quote before, total amount of heap memory abap/heap_area_total or Extended memory em/initial_size_MB then also extended memory(non-dialog WP) and PRIV memory (dialog WP) will be allocated accordingly.