a method for improving the availability of global dos memory under microsoft windows has two primary aspects . first , upper memory blocks are linked to the global heap to increase the amount of global dos memory available . second , a reserved area of global dos memory is maintained to prevent generic memory requests from being fulfilled therefrom . valid requests for global dos memory are intercepted to ensure that they are able to be allocated out of global dos memory or the reserved area . taken in conjunction , the two aspects of the invention substantially decrease the probability that unavailability of global dos memory will result in application or system failure .