1. A system for maintaining security in a distributed computing environment, comprising: an application guard located at a client to manage access by individual transactions to securable components at a client level as specified by a local security policy, the securable components including at least one application wherein said application guard is integrated into said application and controls access to the application with which the application guard is integrated; a policy manager stored on one or more nonvolatile memories located on a server to: create a local security policy derived from a global security policy, said global security policy including a plurality of rules applicable to all application guards in the system, wherein creating the local security policy includes determining which of the plurality of rules of the global security policy are applicable to a particular application guard such that the local security policy contains a fewer number of rules than said global security policy; and distribute the local security policy to said client wherein the local security policy includes the rules customized to the application guard, said rules including a set of grant rules that allow access to securable components and a set of deny rules that prevent access to said securable components; and wherein the application guard receives an authorization request including a subject, an object and a privilege and evaluates said request by matching the rules received from the policy manager to said subject, said object and said privilege in order to control access to said application integrated with the application guard, and wherein the policy manager further receives a modification on an existing global security policy; computes any differences caused by the modification on the global security policy; and commits only the changed portion of the global security policy to an appropriate application guard.