Segment Sizes and Lifetimes in Algol 60 Programs The characteristics of the virtual memory requirements of a sample of Algol 60 programs have been measured. Distributions are presented for thesizes of memory requests and for their holding times (lifetimes). The results are presented in terms of Johnston's contour model and a simple abstract machine. They provide new empirical evidence of certain aspects of the construction and behavior of real programs, and some of their implications for the design of virtual memory systems are presented and discussed. CACM January, 1977 Batson, A. P. Brundage, R. E. virtual memory, program behavior, segmentation, storage allocation, Algol 60, contour model 4.22 4.34 4.45 6.21 CA770105 JB January 3, 1978 12:05 AM 2095 4 3000 2218 4 3000 2218 4 3000 2498 4 3000 2596 4 3000 2734 4 3000 2734 4 3000 2902 4 3000 2911 4 3000 3000 4 3000 3000 4 3000 3000 4 3000 3067 4 3000 1879 5 3000 2095 5 3000 2864 5 3000 3000 5 3000 3000 5 3000 3000 5 3000