1. A computer anomaly detection and software execution management method comprising: monitoring, on each of a plurality of computers running the same operating system, the execution of a software application on each of the computers, wherein the software application is executed in at least one instance on each of the computers; determining stack frame probabilities of encountering various configurations of multiple call stacks at various call stack depths, wherein the call stacks are associated with the instances of the software application on the computers, and wherein multiple snapshots of the call stacks are recorded on the computers responsive to detecting a predefined event in connection with the software application; determining stack frame entropies of various configurations of the call stacks at various call stack depths based on their associated stack frame probabilities; determining stack frame rarity scores of various configurations of the call stacks at various call stack depths based on their associated stack frame entropies in accordance with a predefined rarity function; determining a call stack rarity score of any given configuration of the call stacks as the maximum stack frame rarity score of the given configuration; detecting an anomaly associated with any given one of the computers wherein any of the snapshots recorded on the given computer is of a call stack whose call stack rarity score meets a predefined anomaly condition, and terminating any of the execution instances of the software application on any of the computers with which the anomaly is associated.