A virtual machine computer system permits more than one guest/virtual machine to share a single address space and each control access by its applications to the shared address space. The computer system comprises a host operating system for creating first and second virtual machine guests. The first guest responds to an address space creation request from a first application executing in the first guest to allocate an address space, by determining at least in part a storage region for the address space. The first guest also responds to a request from the first application to grant shared access by a second application executing in the second guest to the address space, by notifying the host operating system that the second guest or the second application is authorized to access the address space. The second guest responds to a request from the second application to access the address space, by determining that the second application has authority to access the address space. Then, the second guest grants access to the second application. The guest and host operating systems both participate in the address translation process for a host managed address space.