em/initial_size_MB
The amount extended memory for all working processes.Under Windows, further memory is assigned dynamically as needed, and you can also set this amount.Ensure that the pool is 10 to 15 times as big as ztta/roll_extension. The exact value depends on the available swap space and the number of users in the host system.
ztta/roll_extension
Specifies how much extended memory can be allocated from the pool to one user context.If ztta/roll_extension_dia or ztta/roll_extension_nondia are not set (DEFAULT.PFL or instance profile), the value in ztta/roll_extension (old procedure) applies for ALL work process types.If, on the other hand, ztta/roll_extension_(non)dia is set, the value in ztta/roll_extension is overwritten for the work process type in question.If the value is exceeded, heap memory is allocated. The work process is assigned only to this user context and is no longer available for other user contexts, since it is switched to the PRIV mode
ztta/roll_extension_dia
This parameter specifies the maximum SAP Extended Memory that can be used for dialog work processes.
ztta/roll_extension_nondia
This parameter specifies the maximum SAP Extended Memory that can be used for non-dialog work processes.
abap/heap_area_dia
This quota restricts the amount of heap memory (Private Memory) that an SAP dialog work process can allocate. This ensures that there is enough swap space available. Heap memory is hardly needed any more with modern 64 bit platforms, as the memory requirement can be satisfied by the SAP Extended Memory. If the consumption of heap memory exceeds the quota abap/heaparea_(non)dia, the user context being executed at this time is cancelled before it can be completed.
abap/heap_area_nondia
This parameter restricts the amount of heap memory (Private Memory) that an SAP non-dialog work process can allocate. This value refers to spool, update, and background processes. This value ensures that enough swap space is available in the system.Local memory is hardly needed any more with modern 64 bit platforms, as the memory requirement can be satisfied by the SAP Extended Memory.If the consumption of heap memory exceeds the quota abap/heaparea_(non)dia, the user context being executed at this time is cancelled before it can be completed.
abap/heap_area_total
This parameter determines the upper limit of heap memory in bytes available to all work processes of an SAP application server.
abap/heaplimit
Private (heap) memory.When this amount is exceeded, a work process is restarted after executing a dialog step.The work process can be run in PRIV mode (private) when the local memory is assigned. This means that the work process is reserved for processing the current user context until the context releases the work process again when the request has ended.
ztta/roll_first
This parameter determines the amount of roll memory in bytes that is allocated to a dialog work process, before SAP Extended Memory is allocated.On 64 bit platforms, where there is sufficient extended emory, the default value of this parameter is 1, the work process therefore is allocated extended memory straight away.
ztta/roll_area
This parameter is used to specify the total size of the roll area, in bytes.The roll area is not important with 64 bit platforms where sufficient extended memory is available.
http://en.vsnew.com/sap-memory-management.html