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By default SAP systems are installed to run in *BASE memory pool on IBM i5/OS. According to the IBM redbook SAP NetWeaver Java on IBM i5/OS, it is recommended to allocate separate memory pool for SAP Java systems due to the overhead of garbage collector. The procedure is outlined in section 4.3.1 of the Redbook. Here is our practice on how to allocate another memory pool for a SAP system, then switch it back.   Step 1. Configure a separate memory pool  Execute WRKSHRPOOL from the command line, and configure *SHRPOOL1 (shared pool 1) with 4GB memory and 100 activity level. (Please review Note 717376 for proper sizing.) image   Step 2. Configure the SAP subsystem description  Execute CHGSBSD against the subsystem description of SAP system, and adjust the pool configuration, like the following  CHGSBSD SBSD(R3SID400/R3_nn) POOLS((1 *SHRPOOL1))  image   Step 3. Configure the routing entry of the subsystem description  CHGRTGE SBSD(R3SID400/R3_NN) SEQNBR(1) PGM(QSYS/QCMD) CLS(R3SID400/R3_NN) POOLID(1) THDRSCAFN(*SYSVAL) RSCAFNGRP(*NO)                                     image Step 4. Start SAP system and verify  A new memory pool should show in WRKSYSSTS, and SAP should run just like before 

To switch the configuration back, we did the following steps

Step 1. Stop SAP system and end the subsystem R3_nn, if it is still active.  Step 2. Adjust the subsystem description to use the *BASE memory pool  CHGSBSD SBSD(R3SID400/R3_nn) POOLS((1 *BASE))  image Step 3. Remove the shared memory pool  Execute WRKSHRPOOL, and specify memory *NOSTG as activity ‘1’ for *SHRPOOL1 image   Step 4. Start SAP and verify that *SHRPOOL1 is not allocated.    

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