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Release 1.1 of the Virtual Machine/Enterprise Systems Architecture™ (VM/ESA™) operating system introduces a new function called VM Data Spaces, provided through a new virtual-machine architecture called Enterprise Systems Architecture/Extended Configuration (ESA/XC). ESA/XC is the strategic VM/ESA virtual-machine environment for Conversational Monitor System (CMS) users and service virtual machines requiring large amounts of storage or advanced data-sharing capabilities. ESA/XC includes all of the facilities of System/370 Extended Architecture (370-XA) that are used by CMS or server programs and is therefore upward compatible for CMS or server programs currently running in 370-XA virtual machines. To this 370-XA base, ESA/XC adds the data space and access-register addressing capabilities previously available only under the Multiple Virtual Storage/Enterprise Systems Architecture (MVS/ESA™) operating system. These addressing extensions can be used to make additional storage available to large, storage-constrained applications and can also be used by servers as an efficient way of sharing data between service virtual machines and the users that access those servers. As an introduction to the VM Data Spaces function, this paper describes the ESA/XC virtual-machine architecture and presents an overview of the VM/ESA services provided in support of the ESA/XC architecture.
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