Increasing the JVM heap size

Some servers might specify a JVM heap size greater than the default. We can increase the heap size of the JVM using the console, wsadmin.sh, or a Java client.

About this task

For a JVM platform running on a 32-bit AIX system, complete this task if the application server, deployment manager, or node agent require a greater heap size.

1. Set attributes that control the heap size for the JVM that is associated with the server.

   (dist)(zos) Use the console, wsadmin.sh, or a Java client to control the heap size.

   (iseries) Use the console or wsadmin.sh to control the heap size.

2. Increase the heap size of the JVM.

   (dist)(zos)

   • Create a script to launch the server. Use the -script option with the command that you are using to start the target server, for example, the startServer, startManager, or startNode batch or shell command utilities. This action generates a script that we can use to launch the target server.

   • Manually set the environment variables before you start the target server with the startServer, startManager, or startNode batch or shell command utilities.

     With the following settings, we can specify a maximum heap size for the JVM of 11 multiplied by 256 megabytes:

     export IBM_JVM_LDR_CNTRL_NEW_VALUE=MAXDATA=0XB0000000@DSA
     export LDR_CNTRL=MAXDATA=0XB0000000@DSA

   • Use the AdminTask object, for example:

     • Jython:

       AdminTask.setJVMMaxHeapSize('-serverName server1 -nodeName node1 -maximumHeapSize heap_size')

     • Jacl:

       $AdminTask setJVMMaxHeapSize {-serverName server1 -nodeName node1 -maximumHeapSize heap_size}

   (iseries) Use the AdminTask object to modify the heap size, as the following examples demonstrate:

   • Jython:
     AdminTask.setJVMMaxHeapSize('-serverName server1 -nodeName node1 -maximumHeapSize heap_size')

   • Jacl:
     $AdminTask setJVMMaxHeapSize {-serverName server1 -nodeName node1 -maximumHeapSize heap_size}

Related tasks

Configure servers

Server settings configuration scripts