The portion of memory used to run recursive procedures has been entirely used. Check if your procedure has many instructions following the recursive line. Following is an example of a procedure that would generate this message. The third line is a recursive call. The procedure calls itself. At each recursive call, MicroWorlds remembers that it still has two more instructions to run. These instructions add up and grow bigger than the area of computer memory allocated for this kind of information.

Example:

to spi-and-unspi :n
fd :n
rt 90
spi-and-unspi :n + 5
fd :n
lt 90
end