Mainframe operating systems are sophisticated products designed to provide a comprehensive and diverse application-execution environment. They make efficient use of system's various resources to effectively process huge amounts of data. They are designed to do highly complex enterprise-level operations easily. They also manage heavy-duty hardware infrastructure efficiently.
There are many types of mainframe operating systems, each for a specific type of enterprise or operation. The popular ones are z/OS, z/VM, z/VSE, Linux for z series and z/TPF.
z/OS operating system
z/OS is a highly secure, scalable, high-performance enterprise operating system from IBM. The current version of z/OS is an upgraded version of OS/390, which evolved from the MVS operating system.
Started as an OS to process only a single program, z/OS evolved into an OS that can handle thousands of programs and users simultaneously. z/OS has some basic recovery, availability, and serviceability (RAS) features that have been core components for decades.
z/VM operating system
z/Virtual Machine is a widely installed virtual machine operating system for mainframe computers which enables commercial use of virtualization.
z/VM is a kind of meta-system that can host other operating systems by providing them each with their own virtual machine. The two major components of z/VM are the Control Program (CP) and the Conversational Monitor System (CMS). While CP artificially creates multiple virtual machines from the hardware resources, CMS is an OS that runs on such a virtual machine and provides interactive user interface and runs applications. z/VM coupled with CMS is a popular system that enables interaction with large number of users and applications.
z/VSE operating system
z/Virtual Storage Extended is the most commonly used operating system for small mainframe machines. Originated as Disk Operating System (DOS), it was the first disk-based OS introduced for mainframe computers. Later DOS became DOS/VS, then VSE/SP, VSE/ESA, and now z/VSE. This OS a provides smaller and simpler base for batch and transaction processing.The design of z/VSE is good for routine production work that consists of multiple batch jobs and transaction processing.
Linux for z series
Linux for z series is often referred to as z/Linux . Few characteristics of Linux for z series include use of traditional disk devices like Count Key Data (CKD) and San connected SCSI, thus it prevents sharing of data with other mainframe operating systems.
Unlike other mainframe operating systems, Linux does not use 3270 display terminals. Instead, X-Windows are standard for graphical interfaces in Linux. Further, Linux operates with the ASCII character set, rather than the EBCDIC character set used on mainframes.
z/TPF operating system
z/Transactional Processing Facility is a special kind of mainframe operating system used for processing very high volume transactions. z/TPF is popularly used by credit card and airline companies. Once called Airline Control Program (ACP), the current version of z/TPF has been extended several times to process high volumes of transactions at higher speeds for very large systems. The OS is capable of handling tens and thousands of transactions per second without interrupting the system's availability.