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A glossary of terms important to IBM mainframe machines

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Z:  Formal design specification used by IBM for software engineering. Developed jointly with the Programming Research Laboratory at Oxford University. Z was apparently key to the design of CICS/ESA Version 3.

z/Architecture:  The design architecture for the eserver zSeries 900, most notably with 64-bit addressing.

z/OS:  The latest name in a long succession for the high end IBM mainframe operating system that began life as OS/360 and reprised that name as OS/390 replaced MVS. Announced October 3, 2000, along with the z/Architecture of the eserver zSeries 900, most notable for its 64-bit addressing and IRD. z/OS also runs on System/390 G5, G6 and Multiprise 3000 systems.

z/OS Firewall Technologies:  A software firewall1 built into SecureWay Security Server, an optional feature of z/OS.

z/OS Management Directory:  An LDAP-based directory that will become the central repository for all z/OS configuration data.

z/OS Unix System Services:  See Unix System Services.

z/VM:  Mainframe operating system which can act as a hypervisor, enabling users to run multiple operating systems on a single machine. There are two main components of z/VM – the hypervisor (CP), which provides the resources to the virtual machines, and CMS1, which provides conversational and timesharing facilities. z/VM replaced VM/ESA October 3, 2000, on the same day that z/Architecture and the eserver zSeries 900 were first announced. z/VM also runs on all but the oldest System/390 systems, even P/390 and R/390. z/VM supports 64-bit addressing. The first release is Version 3.1.

z900:  See zSeries 900.

Zap:  Affectionate name for various utilities (AMASPZAP, aka SUPERZAP in z/OS, or PDZAP in VSE/ESA), which can be used to apply a fix directly to object code in situ). More commonly, used as a noun or verb for the actual change itself that was made using an IBM zap utility. Zapping is a bad thing – it creates programs in which the object code does not agree with the source, and which are hence totally unmaintainable. But it is fun.

ZAP disk:  The virtual disk in z/VM that contains the user-written modifications to VTAM code.

ZAW:  Zero Administration Windows. A Microsoft initiative meant to cut the cost of ownership of a PC by automating the administration of Windows and of changes to a Windows environment. Rarely mentioned anymore, though Active Directory has been quoted as helping it along.

Zero footprint:  Browser-only, thin client, host-access solutions that don’t require any terminal emulation-related applets or software at the client in order to facilitate host interactions. 3270/5250-to-HTML conversion solutions are an example of a zero footprint host access scheme.

Zettabyte:  1024 exabytes, 2 to the seventieth, or 1,180,591,620,717,411,303,424 bytes. It may be some time before you see this scale of storage on your local mainframe. See Yottabyte.

Zipperhead:  IBMspeak for someone with a closed mind. Typically a middle-aged person who remembers the time when you could carry a mainframe operating system around with you on a deck of punched cards, and wishes you still could.

ZISC:  Zero Instruction Set Computing. A chip architecture used in certain specialized semiconductors, such as IBM’s ZISC036 integrated Neural Network chip.

ZPARMS:  z/OS DB2 system parameters, many of which can be changed without shutting down DB2.

zSeries 900:  The mainframes in the IBM eserver family first announced October 3, 2000. All models are air-cooled and support the 64-bit addressing of z/Architecture. None support System/370 mode operation. The initial zSeries 900 models run z/OS, OS/390 V2.6 and above, z/VM, VM/ESA V2.3 and above, VSE/ESA V2.3 and above, and TPF V4.1 and above.