A study of the Allocation Behavior of the SPECjvm98 Java Benchmarks. We present an analysis of the memory usage for six of the Java programs in the SPECjvm98 benchmark suite. Most of the programs are realworld applications with high demands on the memory system. For each program, we measured as much low level data as possible, including age and size distribution, type distribution, and the overhead of object alignment. Among other things, we found that non-pointer data usually represents more than 50% of the allocated space for instance objects, that Java objects tend to live longer than objects in Smalltalk or ML, and that they are fairly small.