IBM® Data Language One (DL/I) Virtual Storage Extended (VSE) is the hierarchical database management system for IBM z/VSE®. IBM DL/I is the language system used to access IBM Information Management System (IMS™) databases and its data communication system. IBM DL/I VSE 1.12.1 is the DL/I release supplied with z/VSE V6.2. It provides increased storage capacity for a DL/I database and its segment types. In an online environment, DL/I executes with CICS® Transaction Server for z/VSE V2.2 on z/VSE V6.2.