Configuring the Windows registry: Increasing the noninteractive desktop heap size

If the parallel engine is installed on a computer that runs Microsoft Windows Server, Standard or Enterprise edition, increase the noninteractive desktop heap size to ensure that a sufficient number of processes can be created and run concurrently.

Before you begin

  1. Log in to Windows Server as the Administrator.
  2. Start the Registry Editor, and back up the Windows Registry. If you plan to make several changes (for example, to configure the parallel engine), create a single backup before you make all the changes.

About this task

IBM® InfoSphere® DataStage® processes are created in a specific desktop heap. Each process consumes a small amount of memory from the desktop heap. If you expect to run many InfoSphere DataStage jobs concurrently, increase the size of the noninteractive desktop heap to allow more processes to be created and run concurrently.

You increase the size of the noninteractive desktop heap by editing the SharedSection parameter string in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems registry subkey. The SharedSection parameter string is located in the Windows registry value and uses the following format to specify heap size:
SharedSection=xxxx,yyyy,zzzz
Where:
  • xxxx specifies the maximum size of the system-wide heap (in kilobytes)
  • yyyy specifies the size of each desktop heap
  • zzzz specifies the size of the desktop heap that is associated with a noninteractive Windows instance
Table 1. The default values for interactive and noninteractive desktop heaps by operating system
Operating system Interactive desktop heap size (SharedSection 2nd value) Noninteractive desktop heap size (SharedSection 3rd value)
Windows Server 2008 (32 bit) 12288 KB 512 KB
Windows Server 2008 (64 bit) 20480 KB 768 KB

Procedure

  1. In the Registry Editor, select the following registry subkey: 
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems
  2. In the right pane of the Registry Editor, locate the Windows registry value.
    1. Right-click the Windows registry value and click Modify.
    2. In the Value data field, locate the SharedSection parameter string, and change the last SharedSection parameter from 512 to 2048.
      For example, specify the following values for this parameter on a 64-bit computer:
      SharedSection=1024,20480,2048

      If you cannot change the size of the desktop heap to 2048, try setting the value to 768. For example, specify the following values for this parameter: 

      SharedSection=1024,20480,768
  3. Click OK and close the Registry Editor.

What to do next

After you make changes to the Windows Registry, restart Windows to apply your changes. If you plan to make several changes (for example, to configure the parallel engine), make all changes before you restart Windows.