DOS/360 and successors: Difference between revisions

IBM released z/VSE 3.1 in 2005. This change in naming reflected the new "System z" branding for IBM's mainframe product line, but did not represent a fundamental change in architecture from VSE/ESA 2.7 which preceded it. In particular, it did not support the new 64-bit z/Architecture, running only in 31-bit mode even on 64-bit capable machines. z/VSE 4.1 released in 2007 introduced support for 64-bit real addressing, with up to 8&nbsp;GB of memory. However, while parts of the supervisor run in 64-bit mode, it only provides 31-bit virtual address spaces to problem state applications. As of 2011 one estimate placed the number of sites using z/VSE at around 40004,000.<ref>{{cite mailing list|url=https://groups.google.com/d/msg/bit.listserv.vse-l/g3fv5ROPc_4/Oc9Y7rGg7zkJ|title=IBM DOS, DOS/VS, DOS/VSE, VSE/SP, VSE/ESA, z/VSE Customers|mailing-list=VSE-L|date=November 2, 2011|access-date=April 25, 2017}}</ref>