Mainframe is an industry term for a large computer, typically manufactured by a large company such as IBM for the commercial applications of Fortune 1000 businesses and other large-scale computing purposes. Historically, a mainframe is associated with centralized rather than distributed computing.

MVS is the operating system that is installed on most of the mainframes. MVS has been said to be the operating system that keeps the world going. The transaction processing and database management programs critical to the world's largest businesses are usually run on an MVS system.

DB2 is a family of relational database management system (RDBMS) products from IBM that serve a number of different operating system platforms. According to IBM, DB2 leads in terms of database market share and performance. DB2 databases can be accessed from any application program.

CICS is an online transaction processing program from IBM that, together with the COBOL programming language, has formed over the past several decades the most common set of tools for building customer transaction applications in the world of large enterprise mainframe computing.

The SMS provides a range of data and space management functions. SMS improves storage space use, controls external storage centrally, and lets you manage storage growth. It makes it easier to convert to new device types. It takes advantage of what available hardware can do.

RACF is the IBM security management product for its mainframe operating system. RACF allows an enterprise to manage the biggest security threat in most enterprises: destruction of computing resources by its own employees.

VTAM is an IBM application program interface for communicating with telecommunication devices and their users. VTAM was the first IBM program to allow programmers to deal with devices as "logical units" without having to understand the details of line protocol and device operation.

JCL is a language for describing jobs to the MVS, OS/390, and VSE operating systems, which run on IBM's S/390 large server computers. These operating systems allocate their time and space resources among the total number of jobs that have been started in the computer.

VSAM is an ACCESS METHOD designed to operate in a virtual storage environment.It is not a DBMS or a Language or a Communication System. The function of a VSAM is to provide an easy way for program to store data on and retrieve data from an external device without concern for a physical details of transferring bytes of data between the program and an I/O device.

The Virtual IP Address (VIPA) adds a layer of protection against network connection failure. A Virtual IP Address (VIPA) is configured on a TCP/IP stack rather than a physical adapter, and is therefore not associated with any particular endpoint device. By configuring multiple paths to a stack using VIPA in combination with conventional IP addresses.