SAP ABAP system memory parameters

ztta/roll_area : Roll area size



Description: The value specifies the size of the roll area in bytes. The roll area is one of several memory areas, which satisfies the user requests of user programs. For technical reasons, however, the first 250 KB or so of a user context are always stored in the roll area, further data



- up to the roll area limit ztta/roll_first,



- in the extended memory, up to the limit ztta/roll_extension or If extended memory is exhausted, then



- again in the roll area, until the roll area is full, then



- in the local process area, up to the limit abap/heap_area_dia



or abap/heap_area_total or until the address space or the swap space is exhausted.



Followed by termination with errors like STORAGE_PARAMETERS_WRONG_SET an error code, that points to memory ottleneck



Aim:



Minimum data transfer with context change; however, the increase helps to avoid problems (address space, swap space, operating system paging)



Unit: Bytes



Dependencies:



rdisp/ROLL_SHM: Should be adjusted because of ztta/roll_area



rdisp/ROLL_MAXFS: Must be adjusted because of ztta/roll_area can be checked by ST02




ztta/hold_data_area: Buffer for User Set/Get Values



Size of the shared memory buffer for user Set/Get data



(System -> User defaults -> Get/Set).



Use: Tuning.



ztta/roll_extension: Short description: Quota for extended memory



Description:



This value specifies the storage quantity in bytes that a dialog user context can allocate (extended memory). The value refers to the storage quantity that an external mode (=SAP window) allocates. When the specified value is exceeded, memory from the roll area is allocated until this is full. Local memory is then allocated.



( Data in the roll area is copied at context change When local memory within the work process is allocated, the work process is assigned to this user context and is no longer available for other user contexts (PRIV mode).) If you set the value too high, a user could cause a bottleneck in the extended memory by increasing his user context. Other smaller user contexts would bring work processes to PRIV mode before their allowed quota is reached.



Objective: Minimize no. of work processes in PRIV mode. Allocate extended memory fairly.



ztta/roll_first : Quota for early allocation in the roll area




Parameter description :



The value specifies the amount of memory in bytes that is allocated from the roll area, before memory is allocated from the extended memory. This means that small user contexts remain complete in the roll area. Any wastage and therefore total consumption of the extended memory can be minimized, because extended memory is assigned to users in granules of a specific length (usually 1 MB).



Only effective in dialog work processes. (Windows NT) Effective in all work processes, due to identical allocation sequence (Windows NT).



Aim:



Optimum usage of the extended memory



ztta/short_area : Size of short-term memory



Parameter description :



Size of memory available in the short term, i.e. until the next "rollout"



The value must be at least 7 times the size of ztta/cua_area



Work area: System




abap/heap_area_dia: Heap memory quota for dialog work processes



Description:



Defines the local process memory quota (heap, malloc) for a user context in a dialog work process. The aim is to avoid a swap space bottleneck if a user context becomes too large.