1. A program compilation execution system comprising: first means which receives a source program including description for generating at least one task and outputs an object program obtained by compiling said source program and information for dividing variables in said source program into groups; second means which receives said object program and said group dividing information, generates an execution format file from said object program and outputs said execution format file, while outputting correspondence information of a group and variables belonging to the group based on said group dividing information; and third means which receives and executes said execution format file and controls in such a manner that when said at least one task is generated, each task reserves a region with a size necessary for the variables belonging to the group corresponding to the task on a memory by referring to said correspondence information.