I haven't tested it but here is what a site says you can do :
"When running Mac OS X, you don't need to manually set an application's memory size for native applications. Mac OS X adjusts the amount of memory as the application requires more or less space. However, you do need to set an application's memory size if you are running an application in Mac OS X's Classic environment. To do this, follow these directions:
1. Determine how much memory is available and accessible to your Mac OS computer. This will give you an idea how much extra memory you can allocate to the application. From the Apple menu, select About This Mac.
2. Make sure the application whose memory allocation you want to increase is closed. Highlight the application's icon.
3. From the File menu, select Show Info. The application's information window should open.
4. In the information window, next to "Show:", select Memory.
5. In the "Preferred size:" field, enter the amount of memory you'd like to allocate to the application. The "Minimum size:" field indicates the amount of free RAM needed to permit the application to run. You cannot change the "Suggested size:" field.
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