Zero administration memory management for the ABAP server
SAP Memory Management is used for the administration of the memory in Application Server ABAP (AS ABAP). With the default settings of profile parameters in SAP Memory Management (zero administration memory management), smooth operation of your system is ensured.
Introducion
Zero administration memory management has been introduced to simplify the administration and maintenance of SAP Memory Management, and to use the available resources optimally. This means that AS ABAP automatically sets default values for the profile parameters in SAP Memory Management, by calculating them dynamically using formulas. The default values of the profile parameters are derived from profile parameter PHYS_MEMSIZE. In your ABAP system, you do not have to configure any profile parameter manually to start AS ABAP.
You do not even have to set parameter PHYS_MEMSIZE, since by default its value is the size of the physical main memory of the server. In an emergency you can override this value.
AS ABAP automatically and sensibly allocates memory to the individual components. This allocation can change during runtime.
For me the most important parameters are:
| Parameters | Default value |
| PHYS_MEMSIZE | Size of the main memory (RAM) |
| em/initial_size_MB | (min(512000, $(PHYS_MEMSIZE) * 0.7)) |
| abap/buffersize | (ceil($(em/initial_size_MB)*1024*0.15/4096) * 4096) |
| abap/heap_area_total | (max($(PHYS_MEMSIZE)*1024*1024 * 0.1, $(abap/heap_area_dia) * 2 )) |
| abap/programs | ($(abap/buffersize)/4) |
| abap/shared_objects_size_MB | (min(20000, $(em/initial_size_MB)*0.02)) |
| em/blocksize_KB | (ceil($(em/initial_size_MB) * 1024 / 100000 / 4096) * 4096) |
| em/global_area_MB | (min($(em/initial_size_MB) * 0.05, 32000)) |
| em/max_size_MB | ($(em/initial_size_MB)) |
| rdisp/PG_SHM | (max(min(1000+40*max(5,floor(($(PHYS_MEMSIZE)-128)*25/128)),16384),1024)) |
| rdisp/max_websocket_connections | ( $(rdisp/tm_max_no) / 2 ) |
| rdisp/wp_ca_blk_no | ($(rdisp/elem_per_queue)*3) |
| rsdb/ntab/entrycount | ($(zcsa/db_max_buftab)) |
| rsdb/ntab/ftabsize | (min(500000, ($(rsdb/ntab/entrycount)))) |
| rsdb/ntab/irbdsize | ($(rsdb/ntab/ftabsize) * 0.2)rsdb/ntab/sntabsize |
| rsdb/obj/buffersize | (max(4096,$(PHYS_MEMSIZE)*1024 * 0.01)) |
| rsdb/obj/max_objects | (max(2000,$(rsdb/obj/buffersize) / 4)) |
| rsts/ccc/cache07 | ($(rsts/ccc/cachesize) * 0.1) |
| rtbb/buffer_length | ($(zcsa/table_buffer_area) * 0.1 / 1024) |
| rtbb/max_tables | ($(zcsa/db_max_buftab) * 0.1) |
| zcsa/db_max_buftab | (max(20000,$(zcsa/table_buffer_area) / (5 * 1024) )) |
| zcsa/table_buffer_area | (min(3333333333, (max(30000000,($(em/initial_size_MB) * 1024 * 1024 * 0.1))))) |
| ES/SHM_MAX_SHARED_SEGS | ( ($(em/global_area_MB) + $(abap/shared_objects_size_MB) + $(rtbb/buffer_length)/1024 + $(zcsa/table_buffer_area)/1024/1024 ) / $(ES/SHM_SEG_SIZE) + 1 ) |
Below You find all the profile parameters in SAP Memory Management together with a description and default values that are valid on 64-bit platforms. The profile parameters are categorized by their functions. Look here.