If you receive an error message saying your modeling tool is out of memory, the application does not have enough memory to operate. You can change the amount of allocated memory directly in the error message dialog or by changing modeling tool properties.

Memory allocation concept

Memory allocation for the product is the same as Java heap size. To increase the amount of memory allocated for the product, simply increase the Java heap size.

Recommended amount of allocated memory

The amount of allocated memory (or Java heap size) should be set to less than the available physical RAM on your computer. To calculate the approximate amount of memory you should allocate, subtract the amount of memory taken by any other processes that will run concurrently with your modeling tool from the total amount of RAM in your computer. Otherwise your JVM process will likely swap, and that will slow down the application.

Do not allocate too much memory

If you increase the Java heap size too much with the 32-bit JVM, you will get an error message that the Java virtual machine cannot be created, and a modeling tool will not start.


The maximum theoretical heap limit for the 64-bit JVM is 4G. In practice, the limit can be much lower, due to various additional constraints such as available swap, kernel address space usage, memory fragmentation, and VM overhead.

  • On most 32-bit Windows systems the maximum heap size ranges from 640K to 800M.
  • On 32-bit Solaris kernels the address space is limited to 2G.
  • On 64-bit operating systems running the 32-bit VM, the max heap size can be higher, approaching 4G on many Solaris systems.
  • On 64-bit VMs, the maximum Java heap size is limited only by the amount of physical memory and swap space your system provides.

Changing the amount of allocated memory

You can set the amount of memory allocated for your modeling tool either in the Environment Options dialog, in the modeling tool properties file, or in the Environment Variables dialog on your machine.


To change the amount of allocated memory in the Environment Options dialog

  1. In the main menu of your modeling tool, go to Options > Environment. The Environment Options dialog opens.
  2. Expand the General options group on the left side of the dialog, and select the Memory Settings category.
  3. In the option specification area on the right side of the dialog, change the value of the Maximum Heap Size or Thread Stack Size option.


To change the amount of allocated memory in the modeling tool properties file

  1. Go to <modeling tool installation directory>\bin and open the modeling tool properties file.

  2. In the JAVA_ARGS line, change the value of the -Xmx property. For example, change the -Xmx800M to -Xmx1066M.

  3. Save and close the file.
  4. Restart your modeling tool.


To change the amount of allocated memory in the Environment Variables dialog on your machine

  1. Go to Control Panel > System and Security > System > Advanced system settings. The System Properties dialog opens.
  2. In the Advanced tab, click Environment Variables. The Environment Variables dialog opens.
  3. In the System variables section, do one of the following:
    1. If the _JAVA_OPTIONS variable is not in the variables list, click New. New System Variable dialog opens.
    2. If the _JAVA_OPTIONS variable is in the variables list, select it and click Edit. Edit System Variable dialog opens.

  4. Set Variable name to _JAVA_OPTIONS and Variable value to the desired memory amount, e.g. -Xmx1066M. Click OK.

    Changing options via the Environment Variables dialog overrides specified options for all Java applications.

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