Support | Mainframe Dictionary | G
A glossary of terms important to IBM mainframe machines
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G2G: Green-to-GUI. A cute term for user interface rejuvenation.
GaA: See Gallium arsenide.
Gallium arsenide: Semiconductor fabrication technique which does away with silicon as the substrate for chip manufacture and uses gallium arsenide (GaA) instead. However, fabrication is expensive, compared with CMOS, and chip yields are low. This has limited its use to supercomputer and military applications. See Silicon/germanium.
GAM/SP: Graphic Access Method/System Product. z/VM facility enabling users to write software for driving IBM graphics systems (e.g., 6090, 5080, 3250, 2250, 2840). Withdrawn June 1997.
Garbage collection: A software technique to free up previously-used, but currently unneeded, storage, typically memory within the allocated address space for a program/application/system. Because the result may be a lot of little pieces of non-contiguous memory, some garbage collection algorithms also include a compaction of the memory that is still in use. Obviously, garbage collection is only required for software that does not automatically release memory along the way, when it first stops being used, though compaction would still be of benefit.
GATE: General Access to X.25 Transport Extension. SNA extension for handling X.25. Configuration option under NPSI.
Gateway: Equipment on a network that enables a terminal on one network to communicate with a terminal on another (incompatible) network. The gateway may convert data formats and protocols as well as physical formats and protocols. Most widely used in the IBM world to connect LANs and SNA networks, where the gateway (often a card plus some software in a PC) converts the NetBIOS protocols into SNA protocols. PADs and protocol converters are typical gateways.
GbE: See Gigabit Ethernet.
Gb Ethernet: See Gigabit Ethernet.
GC: See Garbage collection.
GCD: Graphic Codepoint Definition. Part of the IBM office systems architecture which maps internal character codes onto keyboards and national alphabets. See also CDRA.
GCLISP: Golden Common LISP. See Golden.
GCS: Group Control System. A component of z/VM, intended for use with SNA products, that supports multiprogramming and shared memory support to virtual machines. See VM/SNA.
GDDM: Graphical Data Display Manager. Widely used IBM mainframe package for creating and displaying graphic data on a terminal. Currently available for z/OS, z/VM and VSE/ESA.
GDDM-PGF: GDDM Presentation Graphics Facility. Library of business graphics routines (bar/pie charts, etc) for the GDDM environment. An optional, separately priced feature of z/OS.
GDF: Graphics Data Format/File. Either the data format used internally by GDDM, or a file in that format. May also be used by application programs such as QMF to save charts.
GDG: Generation Data Group. Collection of (z/OS non-VSAM) datasets (see GDS2) all with the same logical name (GDG Base Entry); the individual datasets are uniquely identified by the generation number which is stored as part of the dataset name. The datasets can be referenced either by the explicit generation number or the relative generation number. GDGs are useful where datasets are cycled – standard JCL can be used without having to change the dataset names for each run.
GDLC: Generic/General Data Link Control Interface. Defines a common interface with the same set of commands for multiple DLCs. DLCs that conform to the GDLC interface include Token Ring, IEEE802.3 for Ethernet, Standard Ethernet, SDLC1, QLLC and FDDI.
GDMO: Guidance for Definition of Managed Objects. An ISO standard for object-oriented systems.
GDPS: Geographically Dispersed Parallel Sysplex. A service offering of IBM Global Services that manages z/OS remote copy configuration and storage subsystems, automates Parallel Sysplex operational tasks and performs failure recovery from a single point of control. Comes in two flavors: GDPS/PPRC and GDPS/XRC.
GDPS/PPRC: Geographically Dispersed Parallel Sysplex/Peer to Peer Remote Copy. A hardware-only GDPS approach that synchronously mirrors data residing on a set of z/OS disk volumes to a remote site. cf. GDPS/XRC.
GDPS/XRC: Geographically Dispersed Parallel Sysplex/eXtended Remote Copy. A combination of hardware and z/OS software that performs an asynchronous remote copy. Unlike GDPS/PPRC, no dark fiber is required, and there is no 40km distance limit. See also GDPS.
GDQF: Graphical Display and Query Facility. Displays images – typically CADAM – on high resolution 3270 screens, and/or prepares output for high resolution printers/plotters. Runs on z/OS and z/VM.
GDS1: General DataStream. Under LU6.2, all data sent between TP programs is sent in GDS variables. A GDS variable comprises a length field, an identifier, and the content of the variable.
GDS2: Generation DataSet. One of the dataset1s in a GDG.
GDT: Global Descriptor Table. A set of data structures used in OS/2 to manage memory in a protected mode environment.
Gearbox: Ruggedized shop floor 25MHz 80386PS/2 for CIM1 applications – configured much like a programmable logic controller. Obsolete.
GEM1: Graphics Environment Manager. Obsolete PC GUI from Digital Research.
GEM2: See Tivoli Global Enterprise Manager.
General availability: Perhaps one of IBM’s oldest terms still in use. The time period beginning on the first scheduled day of shipment of a product to customers not involved in beta testing or other early release programs. And ending on the Withdrawal date. More precisely, the Marketing Withdrawal date, as opposed to the end of support. It is always amusing to find Withdrawal dates that are years behind end of support.
General Parallel File System: See GPFS.
General Purpose Register: See GPR.
General Register: See GPR.
General resource: In RACF, anything defined in the Class Descriptor Table (CDT).
General resource profile: A profile used by RACF to protect a general resource.
General user: A RACF user with no security administration privileges beyond: logging on, access to certain resources and control over owned datasets.
Generic character: In RACF, a special pattern-matching characters, such as the asterisk (*), known as wildcard characters in other operating systems, that are invalid in dataset names, but are used in generic profiles to specify all dataset names that match the specified pattern.
Generic Data Link Control Interface: See GDLC.
Generic profile: A resource profile that protects zero or more resources having the same RACF security requirements.
Generic Security Service Application Programming Interface: See Authentication service.
geoGPG: GEOgraphic Graphics Program Generator. AIX geographic information system (GIS) based on a network topological model. geoGPG allows automated mapping and facility management (AM/FM) applications to manage geographically located facilities, assets and events. Announced February 1991 as IBM AIX geoGPG/6000, then renamed IBM geoGPG for AIX December 1995.
Geographically Dispersed Parallel Sysplex: See GDPS.
Geographic Interface for OS/2: See geoInterface.
geoInterface: Geographic Interface. Workstation GIS interface used to visualize, analyze, and update GFIS data. Announced 1996, first for OS/2 then Windows. The OS/2 version was withdrawn April 2001.
geoManager: IBM geoManager Relational Database System. Provides DB2 support for GFIS in z/OS, z/VM, AIX and Windows environments, as well as Oracle support for AIX. The graphic analysis feature allows editing and update of attribute data stored in the database.
GeoPort: Apple standard for real-time telephony on PCs, at one time pursued by Versit as a standard.
GeoRM: See HAGEO/GeoRM.
Gerstner: Lou Gerstner is the man who became Chief Executive of IBM in April 1993 (it just had to be April the 1st, didn’t it?). His background was in biscuits (leading to suggestions that he must be crackers) and charge cards. The non-computer background augured well, since he’s not carrying the burden of a lifetime’s immersion in the IBM culture.
GF11: IBM supercomputer development project.
GFIS: Geographic Facilities Information System. IBM GIS system. See also geoInterface.
Gibson Mix: A synthetic workload (benchmark) used by IBM to calculate the effective MIPS ratings of its large processors. Effectively it measures the average execution time of a mix of instructions.
GID: Group Identifier. A string of one to eight characters that identifies a RACFgroup. In AIX1 and z/OSUnix System Services, a number that uniquely identifies a specific group name.
GIF: Graphics Interchange Format. A standard for defining raster (bit-mapped) images, whose wide popularity suddenly dropped after Unisys declared that it would be asserting its intellectual property rights in it. Largely being replaced by JPEG though you still see a lot of GIFs on Web pages.
Gigabit: 1,073,741,824 bits. Abbreviated as Gb1.
Gigabit EtherChannel: See EtherChannel.
Gigabit Ethernet: A standard for Ethernet using optical fiber cable to obtain 1Gbps data transfer rates.
Gigabyte: Roughly a billion (American) bytes. Actually it’s 1,073,741,824 bytes – but who’s counting? Abbreviated as GB.
GigaFLOPS: 1000 million FLOPS. Measure of supercomputer performance.
Giga processor: The name of the eserver pSeries in the media when it was still in the rumor stage.
GIO: Growth Incentive Option/Offer. IBM marketing program. Basically you get a whopping discount on upgrades if you commit to them early.
GIOP: General Inter-ORB Protocol, an OMG standard that specifies the transfer syntax and message formats for communication between ORBs.
GIS: Geographic Information Systems. Systems which manage geographic information for map making, demography, geology, and the like. It has proved a lucrative market sector over the last 15 years, and IBM has set up a number of joint ventures to exploit it (e.g., with the University of California at Santa Barbara, UGC, the geoGPG product, and the National Center for Geographic Information and Analysis).
GKS: Graphical Kernel System. ISO graphics standard. Supported by IBM in GDDM and the GDDM-GKS interface.
Glasshouse: The mainframe machine room (also known as the Raised floor).
Glass teletype: A generic name for dumbCRTs. More strictly it’s used to mean terminals which appear to be teletypes as far as other devices are concerned, but which have a screen rather than a roll of paper as the output medium. Obsolete.
GLISP: Golden Common LISP. See Golden.
Global access checking: A RACF performance feature that allows certain resources to be security checked against an in-storage table.
Global Financing: IBM Global Financing. The largest lender of money in the Computing world, to the tune of $20 billion to customers and another $30 billion to business partners. Operates in 40 countries. Is also behind Capacity Upgrade on Demand, financing the spare hardware until it is required.
Globally RACLISTed profiles: In-storageprofiles for RACF-defined resources that are shared with other RACF nodes. See also RACLISTed profile, locally RACLISTed profiles.
Global Network: A division of IBM which AT&T bought in December 1998 for $5 billion cash. As part of the deal IBM outsourced a large amount of its global networking needs to AT&T, which in turn outsourced certain applications processing and data center management back to IBM.
Global Services: IBM Global Services. IBM’s consulting practice, averaging 50,000 consultants at work worldwide. Outsourcing is about 40% of the business.
GMF: Graphics Monitor Facility. See NGMF.
GML: Generalized Mark-up Language. The language for specifying output formats in the SCRIPT system. See also SGML, SCRIPT/VS, DCF.
GMLC: Graduated Monthly License Charge. A monthly charge for mainframe software based on the power of the processor on which the software is to run. Introduced at the beginning of 1989, superseding the flat monthly license charge (MLC). Currently available for z/VM, but not z/OS. See also GOTC, FMLC, IMLC.
GMR: Giant MagnetoResistive head. IBM-developed technology for enhanced hard drive capacity. First deployed commercially in November 1997, in the Deskstar 16GP, a 16.8-gigabyte drive.
GNM: NetCenter Graphic Network Monitor. See NetCenter.
Go: See Domino Go Webserver.
Goal mode: A mode of processing within Workload Manager (WLM) where the active service policy determines system resource management. The alternative is Compatibility mode where the IEAIPSxx and IEAICSxx parmlib members determine system resource management. The z/OS Intelligent Resource Director requires that WLM be running in Goal mode.
GOCA: Graphics Object Content Architecture. Defines the structure and content of graphic image data. Includes location and content of lines, curves, drawing orders, etc. Superset of the I/O graphics standards of IPDS.
Godzilla: Slang terminology used by systems programmers for SMS1. Named because the main module of SMS is called IGDZILLA.
GOLC: Growth Opportunity License Charge. A monthly IBM software fee for the operating system and systems software introduced September 1999 to support the System/390 Multiprise 3000 line of small mainframes. Initially, GOLC provides a discounted price based on the size of the previous processor, then continues with a lower price that recognizes the size (small) of the Multiprise 3000. Includes both z/OS and z/VM.
Golden: Golden Common LISP. LISP learning tool and development environment for PC-DOS from Gold Hill Computers. Announced December 1985 as an IBM Program Offering. Withdrawn June 1987. Abbreviated as GCLISP and GLISP.
Golden Screwdriver: In the old days when a customer ordered the smallest mainframe in a range IBM had the option of shipping a machine with a bigger processor and more memory but with software which prevented the extra power and storage being exploited. If the customer at a later date wanted an upgrade then an engineer would arrive with his golden screwdriver and erase the code which was slowing down the machine. The result was a more powerful machine and a huge invoice for the upgrade.
Gopher: An Internet protocol, developed at the University of Minnesota, that provides a menu-driven interface for accessing files and information on other computers. The protocol was named Gopher after the Minnesota University mascot, the Golden Gopher. Few Internet sites use Gopher anymore, as HTTP-based Web sites offer more flexibility.
GOSIP: Government Open Systems Interconnection Procurement/Profile. A Government standard for communications based on OSI and TOP developed in the US, UK, Germany, and France. Obsolete.
GOTC: Graduated One Time Charge. One time charge for IBM software introduced at the beginning of 1989. Unlike OTC, the GOTC varies according to the processor for which the software is licensed. At the beginning of 1999, OTC and GOTC options were dropped from any mainframe software product for which a monthly charge option was available. See also GMLC.
Governor: See DB2 Governor.
GPFS: General Parallel File System. GPFS for AIX is a shared disk file system for parallel and serial applications. GPFS for Linux is similar but for Red Hat Linux running on xSeries.
GPR: General Purpose Register. Also known as a General Register (GR). 370-architecture machines have 16 GPRs each of 32 bits. ESA augments the GPRs with a set of Access Registers.
GPS: General Purpose System. Occasional IBMspeak for small business systems (e.g., iSeries 400).
GPSI: General Purpose System for Inferencing. Expert system used in the RT PC for diagnostic services. Developed at the University of Illinois with IBM funding. Obsolete.
GPT: Generalized Path information unit Trace. A record of the flow of path information units (PIUs) between a network control program and its resources.
GR: General Register. See GPR.
Graduated Monthly License Charge: See GMLC.
Granularity: Although it can refer to level of detail in almost any context, granularity is more commonly used to refer to the closeness of the incremental power steps in a manufacturer’s processor range. A highly granular range is one where you can move to a more powerful processor without having to buy one far too big for your needs. The IBM mainframe range is pretty granular today, although it hasn’t always been so in the past, and some of the PCM vendors had a fine old time filling the gaps in a non-granular (lumpy?) IBM range.
GraphicsView/2: SystemView graphics application on OS/2 EE. Provides an SAA-conformant graphical interface for displaying network configurations to help the operator interpret LAN management data. Announced September 1990. Withdrawn September 1997.
graPHIGS: Support for the ANSI PHIGS standard. Originally in stand-alone products, but now included in AIX.
Green card: The name given by system programmers for the IBM mainframe reference summary booklets, no matter what the color. Named because the original System/360 versions were green fan fold cards. At least, the size remains the same: just right for slipped into a shirt pocket. The problem, of course, is the lack of shirt pockets in much of today’s attire.
Group: Zero or more users defined with the same security requirements for specified RACF resources.
Group authority: Which RACF functions a user can perform on a group: USE, CREATE, CONNECT or JOIN.
Group dataset: A dataset with a qualifier with the same name as a RACF group name. Normally, the high level qualifier, but installations can choose another qualifier.
Group ID: In RACF, now known as group name.
Grouping profile: A RACFprofile in a resource grouping class.
Group name: One to eight characters that uniquely identifies a group to RACF.
Group polling: Enhancement to NCP and 3174firmware enabling substantial reduction in polling overhead when a 3174 gateway has a large number of DSPUs.
Group profile: The RACFprofile that defines a group.
Group-related user attribute: Allows a user to control RACF security for a group and its subgroups.
Groupware: Once a popular buzzword for software which provides support for groups of people working collaboratively on projects. IBM’s principal groupware offering is the Notes software from its Lotus subsidiary. See also Person to Person.
GRPACC attribute: Gives all RACF users in a group UPDATE authority to any group datasets created by any user in the group.
GRS: Global Resource Serialization. z/OS subsystem for sharing resources in a multisystem environment, including a sysplex, to ensure data integrity. See also Dequeue, Enqueue.
GSAM: Generalized Sequential Access Method. A feature of IMS1.
GSD: General Systems Division. GSD used to be one of the three major product divisions of IBM (see DPD, OPD). The System/3x products originated in GSD, evolving into the iSeries 400.
GSE: See GUIDE SHARE Europe.
GSE U.K.: The United Kingdom section of GUIDE SHARE Europe.
GSKit: IBM Global Security Kit. Provides SSL security.
GSS API: Generic Security Service Application Programming Interface. See Authentication service.
GTA: General Trading Architecture. IBM architecture for financial (e.g., stock exchange type) applications.
GTF: Generalized Trace Facility. An optional z/OS utility that records system events, which can be used for problem diagnosis. Events such as supervisor calls and start I/O operations are recorded. Very resource greedy (up to 20% of processor cycles) but useful for intractable system problems.
GTMOSI: General Teleprocessing Monitor for OSI. z/OS CICS teleprocessing monitor providing tools to help users write native OSI applications at layers 6 (presentation) and 7 (application). Offers protocol conversion between OSI and SNA. The combination of GTMOSI, OSNS, and OTSS is an OSI analog of CICS. IBM pronounced it Je t’aime OSI, although the words probably stuck in the corporate throat. Replaced by CSFI.
Guest: A second operating system that runs on the user’s primary operating system – e.g., VSE/ESA running as a guest under z/VM.
GUI: Graphical User Interface. Generic term for the WIMPS type interfaces used in OS/2, Windows, and the Macintosh. IBM has been involved to varying degrees in any number of GUIs – see AIXwindows, CUA1, Metaphor, Motif, NeXTStep, OpenLook, Presentation Manager, Windows, X-Terminal, X-Windows.
GUIDE: Guidance for Users of Integrated Data processing Equipment. For many years, an international user group for users of large IBM equipment. Main GUIDE interests were in applications and the commercial world. Depending on the area of the world, either stepped aside for SHARE or merged with SHARE. See also International User Group Council.
GUIDE SHARE Europe: An IBM user group serving Europe. Formed by the merging of the local SHARE and GUIDE chapters. See also GSE U.K.
GUI Facility: A set of z/VM workstation agents, help files and modules available from the VM Download Library.
GW/NCP: Gateway NCP. Version of NCP software used with SNI to enable separate SNA networks to talk with one another. See also Gateway.
GW/SSCP: Gateway SSCP. An SSCP which acts as a gateway between two independently administered SNA networks in an SNI environment.
GW/VTAM: Gateway VTAM. Version of VTAM software used with SNI to enable separate SNA networks to talk with one another. See also Gateway.