AS/400 Configuration Memory Management

Implementing the memory management system on AS/400 is described in Implementation on Platforms for IBM AS/400.

In the following tables, you will find information about the necessary settings for the memory management system.

• Check if your host system fulfills the SAP recommendations for main memory and swap space.

Check the resources and system-specific requirements on all host systems on which an R/3 server is to be installed. For more information, see Checking the Hardware and Operating System of the Host System.

• Set the R/3 profile parameter that uses the memory management system.

Set these parameters in the instance profile used by each R/3 application servers in your system. For more information, see the CCMS Guide.

If you modify the profiles directly with a system editor, you must perform an error check. For more information, see Checking the Hardware and Operating System of the Host System.

The values listed in the following table for the host systems and servers should ensure the best possible operation of your R/3 application sever.

Main Memory and Swap Space on the Host System

Resource	SAP Recommendation
Free memory area ASP 1	Minimum: 2 GB Recommend 4-6 GB
Main memory	512 MB is sufficient for approx. 15 dialog users. 1024 MB is sufficient for approx. 50 dialog users. You will achieve performance advantages with higher values. These values are valid for hosts on which only one R/3 server runs. If other servers run on the host, contact the Hardware Competence Center or your system consultant.
Memory pool 2	All R/3 jobs run in pool 2 according to the default values. Therefore, make as much space available for pool 2. 150-200 MB is the absolute minimum.

R/3 Profile Parameters

Parameter	Recommended Value
abap/heaplimit	20000000 (20 mil. bytes)
abap/heap_area_dia	200000000 (200 mil. bytes)
abap/heap_area_nondia	2000000000 (2 GB)
abap/heap_area_total: Limit for Heap Memory	2000000000 (2 GB)
em/initial_size_MB: Size of the Extended Memory Pool	128 (128 MB, 6 MB per user) Minimum 64 MB
em/stat_log_size_MB: Statistics - User Context Size	20
em/stat_log_timeout: Statistics - User Context Size	600
rdisp/ROLL_MAXFS: Maximum Roll File Size	0
rdisp/ROLL_SHM: Roll Buffer Size	0
rdisp/PG_MAXFS: Maximum Size of the R/3 Paging File	16384 blocks
rdisp/PG_SHM: Size of the Paging Buffer	16384 blocks
ztta/roll_area: Roll Area	16773120 (16 MB roll area per internal mode)
ztta/roll_first: Size of the Initial Allocation from the Roll Area	16773120 (16 MB roll first)
ztta/roll_extension: Limit for Extended Memory	20000000 (20 MB extended memory per user)

Parameter	Recommended Value (Use)
em/stat_log_size_MB	20 (Size above which the user context is logged for statistical purposes)
em/stat_log_size_timeout	600 (Interval in which statistics are gathered for the user context size)
rdisp/PG_MAXFS	8192 (Maximum size of the ABAP paging file - 64 MB)
rdisp/PG_SHM	8192 (Size of the paging buffer - 64 MB)

The values listed here are recommended basic values. In the course of monitoring and optimizing your R/3 System, you may have to change these values under certain circumstances. For more information, refer to Monitoring the Memory Management System and Temporary Memory on AS/400.

Check the changes to the system profiles using the program sappfpar. For more information, see Checking the Hardware and Operating System of the Host System.