PURPOSE: To always detect destruction in the case that an area assigned to another task is destroyed irrespective of whether it bestrides the boundary of the area or not by filling up a whole area pool for the task with a specified character.

CONSTITUTION: As for the area pools prepared in the number of the tasks, the whole area is filled up with the specified character at the time of starting the task, and the whole area pool is checked on the occasion of an area release request and module link, etc., and when the destruction of the specified character in the area other than that assigned to that task is detected, a warning is issued. In the area pool (i) corresponding to the task (i), the whole area is filled up with the specified character (*) at the time of starting the task (i), and the whole area pool (i) is checked on the occasion of the area release request and the module link, etc. In this case since (*) is painted out by another character (in this case, Z) in the area other than that assigned to the task (i), it is considered to be the destruction of the area assigned to another task, and the warning is issued.