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)) Step 3. Remove the shared memory pool Execute WRKSHRPOOL, and specify memory *NOSTG as activity ‘1’ for *SHRPOOL1 Step 4. Start SAP and verify that *SHRPOOL1 is not allocated.