E3 Server stores function calls in a temporary structure at run time called thread stack and, as functions are processed, they are removed from this stack. Although it is not recommended, the size of this stack can be adjusted using the Runtime thread's stack size (megabytes) item. Its edition field must have a numerical value that specifies the size of this stack in megabytes to use.

If this item is not modified, the stack value is fixed in four megabytes. In case this item is modified, a value of 0 (zero) is a special value that means Windows default value must be used, which is 1 (one) MB on more recent versions. Values between one and three allow reducing stack size, which is not recommended. Values higher than 256 are limited to 256.