1. A computer program product for virtualizing information technology (IT) appliances comprising a computer readable storage medium having computer usable program code embodied therewith, the computer usable program code comprising: IT application hosting facilities software implemented at a layer of abstraction above a z/VM based host, which is implemented in a layer of abstraction above SYSTEM Z hardware, where the IT appliance hosting facilities software comprises programmatic code functioning as virtualized hardware upon which a plurality of IT appliance software modules are able to concurrently run, wherein the IT appliance hosting facilities software layer is configured to provide caching, application level security, and an standardized framework for running the plurality of IT appliance software modules configured in conformance with the standardized framework, wherein said IT appliance hosting facilities software comprises: an appliance runtime environment configured to abstract host system details from IT appliance software modules, wherein the appliance runtime environment is completely dependent upon resources of the z/VM based host; and platform support configured to provide a plurality of services specific to said IT appliance hosting facilities that are able to be invoked by components of the appliance runtime environment.