A method, system and computer program product for generating appropriately sized core files used in diagnosing application crashes. An instruction pointer corresponding to the instruction that led to the application crash is identified. Address ranges of the garbage collection module and the compiler module are obtained. A determination is made as to whether the address of the instruction pointer lies within any of these address ranges for each stack frame in a crash stack. If it does not, then read or write instructions executed prior to the instruction that led to the application crash are identified for each stack frame in the crash stack. If a value of a register involved in such read or write instructions is within the address range of the compiled code buffers and/or heap, then the compiled code buffers and/or heap need to be included in the core file; otherwise, they do not.