For IBM i OS operating system

Tuning JVM settings on IBM i

To improve WebSphere Commerce performance, the WebSphere Application Server JVM settings require tuning. After you create the WebSphere Commerce instance, the default JVM arguments on IBM i are empty. Change the default behaviors using the steps in this task to improve performance on the WebSphere Commerce server.


  1. Open the WebSphere Application Server administrative console.
  2. Click Servers > Server Types > WebSphere application servers > server_name where server_name is the name of the WebSphere Commerce server.
  3. In the Server Infrastructure section, click Java and process management > Process definition > Java virtual machine.
  4. Set the Generic JVM arguments: -Xgcpolicy:gencon -Xmns256m -Xmnx512m -Xjit:codetotal=131072
    Note: Set Xgcpolicy:gencon when you are using a generational garbage collector. The generational schema attempts to achieve high throughput, along with reduced garbage collection pause times. To accomplish this goal, the heap is split into new and old segments. Long-lived objects are promoted to the old space while short-lived objects are garbage collected quickly in the new space. The gencon policy provides significant benefits for many applications. However, it is not suited for all applications, and is typically more difficult to tune.