SAP Library - Find your answers

Use

This sets the upper limit for the heap memory that all work processes of an R/3 application server can allocate. You can use this upper limit to restrict the swap space usage of an R/3 application server to a specific amount. You can find more details on this topic under Functions of the R/3 Memory Management System.

This value ensures that even at maximum swap space usage of the R/3 System and during normal operation, at least 100 MB swap space (or approximately 10-15%) remains free.

Integration

• Swap space size in the system. In addition to the system and R/3 requirements, another swap space reserve of at least 100 MB should be available. You can find more details on this topic under
Swap Space Requirements and Functions of the R/3 Memory Management System.
• R/3 Extended Memory pool size (parameter em/initial_size_MB). The swap space size that an R/3 server can fill orients itself primarily according to the R/3 Extended Memory pool and the value of this parameter.

Unit: Bytes

Default value: 800000000 (800 MB)

Recommended value: A general value cannot be specified here. The deciding factor for the setting is the available swap space. You must set the parameter to the following value:

• physical memory + swap space - allocated virtual memory

You can monitor physical memory and swap space using Transaction ST06 (see Checking Unused Working Memory using Transaction ST06) Allocated virtual memory consists of allocated memory from:

• All R/3 instances
• Database buffers and database processes
• Operating system, special file system cache

You can view this using Transaction ST02 ® Detail Analysis Menu ® Storage.

You can find the values from the configuration examples (Contents button): Setting Up the Memory Management System

Changes: Customers can make changes.

Use

This parameter sets the limit for the heap memory (heap memory) that an R/3 non-dialog work process can allocate. This value refers to spool, update, and background processes. This value ensures that there is enough swap space available in the system.

In IBM AIX systems, specify a value for this parameter smaller than 200 MB, since the shared memory areas under AIX have a limited size. For Siemens-Nixdorf SINIX, 350 MB is the maximum that you can specify. A higher value has no advantages and no effects.

Goal:

Prevent a single non-dialog work process (user context) from filling up the entire heap memory of the application server.

The work processes of an application server can allocate only so much heap memory as specified in parameter abap/heap_area_total. The limit specified in the parameter refers to the combined heap memory usage of all work processes for an application server.

The value should be high enough for the largest possible background processing context in your R/3 System. If the value is too small, the background process is allocated R/3 Extended Memory. This Extended Memory is not available for dialog work processes.

The default value is generously sized and does not usually have to be increased.

Unit: Bytes

Default value: 40000000 (40 MB)

Recommended value For the following platforms:

• IBM AIX: 190000000 (190 mil. bytes)
• Siemens-Nixdorf SINIX: 350000000 (350 mil. bytes)
• HP-UX: 600000000 (600 mil. bytes)
• Other platforms: 900000000 (900 mil. bytes)

You can find the values from the configuration examples (Contents button). You can find additional restrictions under Data Segment Size (UNIX).

Changes: Customers can make changes.

Use

Set the limit for the heap memory ( Private Memory) that an R/3 dialog work process can allocate. This ensures that enough swap space is available.

If the value is exceeded, the user context that was just executed is terminated prematurely.

In IBM AIX systems, specify a value for this parameter smaller than 200 MB, since the shared memory areas under AIX have a limited size. A higher value has no advantages and no effects.

Prevent a single dialog work process (user context) from filling up the entire heap memory of the application server.

A work process from an application server can allocate only so much heap memory as specified in parameter abap/heap_area_total. The limit specified in the parameter refers to the combined heap memory usage of all work processes for an application server.

Ensure that the value is high enough to fulfill all the regular memory requirements, but is not so high that the work process runs up against the swap space limit of the operating system. See the graphic in Abap/Heaplimit: Work Process Restart.

Unit: Bytes

Default value: 80000000 (80 MB)

Recommended value: 2 GB, if the operating system does not set a lower limit. You can find values in the configuration examples (Content button).

Changes: Customers can make changes.