Mainframe Definitions:
Mainframe is a High performance Multi User computer
system which is the most scalable, available, reliable
and secure machine in the world capable of handling
numerous terminals and peripherals simultaneously.
What is Terminal
A device, usually equipped with a keyboard and display
device (without a CPU), capable of sending and receiving
information over a network.
IBM 3270 terminals are used to connect to a mainframe
computer.
What is Emulator
Emulator is a computer program that duplicates the
functions of an IBM 3270 mainframe terminal which was
used to connect to a mainframe computer.
IBM no longer manufactures
3270
terminals, instead we use a PC running a software that
mimics the IBM terminal. This software is called as
Terminal Emulator.
What is a Mainframe Channel
A mainframe channel
connect to one or more controllers via either pairs of large
"bus and tag" cables or, fiber optic ESCON (Enterprise
System CONnection) cables and FICON (Fibre Connection),
which has the ability controlling one or more devices. This
is one of the important term in mainframe technology since
it has the ability of take care of huge input and output
functions.
Batch processing
Batch applications are processed on the mainframe
without user interaction. A batch job is submitted on
the computer; the job reads and processes data in bulk—
perhaps terabytes of data— and produces output, such as
customer billing statements.
Online
processing
Transaction processing
that occurs interactively with the end user is referred
to as online transaction processing or OLTP.
Examples include:ATM machine transactions such as deposits, withdrawals,
inquiries, and transfers
Supermarket payments with debit or credit cards
Airline Ticket booking over the Internet
IBM DEFINITIONS:
Abend
Abnormal end. End of a task or job because of an error
condition that cannot be resolved by system recovery
facilities while the task is performed.
API
Application programming interface. A software interface
that enables applications to communicate with each
other. An API is the set of programming language
constructs or statements that can be coded in an
application program to obtain the specific functions and
services provided by an underlying operating system or
service program.
Assembler
A
computer program that converts assembler
language instructions into binary
machine language (object code
Binder
A system program that processes the
output of language translators and compilers into an
executable program (load module or program object). It
replaces the linkage editor and batch loader in the MVS
operating system.
Buffer
A portion of storage used to hold input or output data
temporarily
Buffer
PoolA group of identical buffers that can be used
interchangeably. The purpose of buffer pools is to cache
table and index data from disk. All databases have their
own buffer pools.
Cache
A special-purpose buffer storage, smaller and faster
than main storage, used to hold a copy of instructions
and data obtained from main storage and likely to be
needed next by the processor.
Catalog
A directory of data sets, with reference to
their locations.
Cataloged
data set
A data set that is represented in
an index or hierarchy of indexes that provide the means for
locating it.
Cataloged
procedure
A set of job control language (JCL) statements placed in
a library and retrievable by name.
Cluster
A group of interconnected computers that are working
together as one unit.
COBOL
Common Business-Oriented Language
(COBOL). A high-level language, based on English, that
is primarily used for business applications.
CommArea
A communication area made available
to applications running under CICS.
Commit
A request to make all changes to
resources since the last commit or backout or, for the first
unit of recovery, since the beginning of the application.
Compiler
A program that translates a source program into an
machine executable program
Compiler
options
Keywords that can be specified to control certain
aspects of compilation. Compiler options can control the
nature of the output generated by the compiler, the
types of printed output to be produced, the efficient
use of the compiler, and the destination of error
messages.
Condition
code (Hardware)A two bit
data area that many instructions set to summarize the
result of executing the instruction. For example, an Add
instruction may set the condition code to 00 to indicate
the result of the instruction is 0, 01 to indicate the
result is negative, 10 to indicate the result is greater
than 0, or 11 to indicate the result represents an
overflow; it is greater than the capacity of the output
area.
Condition
code (Software)A 12-bit binary value many programs set to indicate the
result of running the program. This code is often
referred to as a return code.
Console
An input/output device on a computer, reserved for
communication between the computer operator or
maintenance engineer and the computer.
Control interval
A fixed-length area or disk in which VSAM stores records
and creates distributed free space. Also, in a
key-sequenced data set or file, the set of records that
an entry in the sequence-set index record points to. The
control interval is the unit of information that VSAM
transmits to or from disk. A control interval always
includes an integral number of physical records.
Control Unit
A device that coordinates and
controls the operation of one or more input/output devices,
and synchronizes the operation of such devices with the
operation of the system as a whole.
CICS
Customer Information Control System, An online
transaction processing (OLTP) system that provides
specialized interfaces to databases, files and terminals
in support of business and commercial applications. CICS
enables transactions entered at remote terminals to be
processed concurrently by user-written application
programs.
Cylinder
On a magnetic disk or in an
assembly of disks, the set of all tracks that can be
accessed by all the magnetic heads of a comb in a given
position, without repositioning the access mechanism.
DFSORT
An IBM licensed program that is a
high-speed data-processing utility. DFSORT provides an
efficient and flexible way to handle sorting, merging, and
copying operations, as well as providing versatile data
manipulation at the record, field, and bit level.
DFSMSdfp
A DFSMS/MVS functional component that
provides functions for storage management, data management,
program management, device management, and distributed data
access.
DFSMSdss
A DFSMS/MVS functional component used
to copy, move, dump, and restore data sets and volumes.
DFSMShsm
A DFSMS/MVS functional component used
for backing up and recovering data, and managing space on
volumes in the storage hierarchy.
DFSMSrmm
A DFSMS/MVS functional component that
manages removable media.
DASD DASD stands for Direct Access Storage Device.
This indicates to any type of storage that was directly (randomly) addressable independent of the location of the data.
Data
set
A named collection of related data records that is stored
on disk or tapes. Almost equivalent to a file
in Windows operating system. But a data set differs from
a 'file', in that it has a defined format, as opposed to
a file that is just a collection of data with no defined
format in Windows.
DBMS
Database management system, A
software system that controls the creation,
organization, and modification of a database and the
access to the data that is stored in it.
DB2IBM relational database management system.
Deadlock
An error condition in which processing cannot continue
because each of two elements of the process is waiting
for an action by or a response from the other.
Duplexing
The process of writing two sets of
identical records in order to create a second copy of data.
GDG
Generation data group, A
collection of historically related non-VSAM data sets
that are arranged in chronological order; each data set
is called a generation data set.
Hub
In a network, a point at which circuits are either
connected or switched.
IDCAMS
An IBM program used to process
access method services commands. It can be invoked as a
job or jobstep, from a TSO terminal, or from within a
user's application program.
IMS
Information Management System,
Any of several system environments available with a
database manager and transaction processing that are
capable of managing complex databases and terminal
networks.
ISPF
Interactive System Productivity
Facility, A dialog manager for interactive applications. It
provides control and services to permit execution of
dialogs.
Interrupt
A suspension of a process, such as the execution of a
computer program, caused by an event external to that
process, and performed in such a way that the process
can be resumed.
JCL
Job control language, A
sequence of commands used to identify a job to an
operating system and to describe a job's requirements.
JESJob entry subsystem, A system
facility for spooling, job queuing, and managing I/O.
JobA
unit of work for an operating system.
Jobs are defined by JCL statements.
Load
moduleAn executable program stored in a partitioned data set
program library.
Logical
partition (LPAR)A subset of a single system that contains resources
(processors, memory, and input/output devices). A
logical partition operates as an independent system. If
hardware requirements are met, multiple logical
partitions can exist within a system. Normally this
feature is implemented in all the
mainframe systems. By this feature it is
possible to create partitions and by
which CPUs and I/O sub-systems can be
shared between logical partitions.
Multiprocessing
The simultaneous execution of two or more computer
programs or sequences of instructions.
Multitasking/Multithreading
Mode of operation that provides for the concurrent, or
interleaved, execution of two or more tasks, or threads.
Nonvolatile storage
Additional
random access electronic storage with a
backup battery power source, available
with an IBM Cache Storage Control, used
to retain data during a power outage.
Nonvolatile storage, accessible from all
storage directors, stores data during
DASD fast write and dual copy
operations.
Parallel
processingThe simultaneous processing of units of work by many
servers. The units of work can be either transactions or
subdivisions of large units of work (batch).
PDSPartitioned data set, A data set in direct access
storage that is divided into partitions, called members,
each of which can contain a program, part of a program,
or data.
PDSEPartitioned data set/Extended,
A system-managed data set that contains
an indexed directory and members that
are similar to the directory and members
of partitioned data sets. A PDSE can be
used instead of a partitioned data set.
PL/I
A general purpose scientific/business high-level
language. PL/I is a powerful procedure-oriented language
especially well suited for solving complex scientific
problems or running lengthy and complicated business
transactions and record-keeping applications.
RACFResource Access Control Facility, An IBM security
manager product that provides for access control by
identifying and verifying the users to the system,
authorizing access to protected resources, logging the
detected unauthorized attempts to enter the system and
logging the detected accesses to protected resources.
REXX
Restructured
extended executor, A general-purpose, procedural
language for end-user personal programming, designed for
ease by both casual general users and computer
professionals. It is also useful for application macros.
REXX includes the capability of issuing commands to the
underlying operating system from these macros and
procedures.
Reentrant
The attribute of a routine or
application that allows more than one user to share a single
copy of a load module.
Return
code
A code produced by a routine to
indicate its success or failure. It may be used to influence
the execution of succeeding instructions or programs.
SDS
Sequential data set, A data set in
which the contents are arranged in successive physical
order and are stored as an entity. The data set can
contain data, text, a program, or part of a program.
Contrast with partitioned data set (PDS).
SDSFSystem Display and Search
Facility, A panel-based product that provides detailed
information about jobs and job output, devices and other
resources in a z/OS system.
SMFSystem management facilities. A
z/OS component that provides the means for gathering and
recording information for evaluating system usage.
SMSSystem management Subsystem. A DFSMS/MVS facility used to automate and centralize the management of storage. Using SMS, a storage
administrator describes data allocation characteristics, performance and availability goals, backup and retention requirements, and storage requirements to the system through data class, storage class, management class, storage group, and ACS routine definitions.
Temporary data set
An uncataloged data set whose name begins with & or &&, that is normally used only for the
duration of a job or interactive session. Contrast with permanent data set.
Transaction
A unit of work
performed by one or more transaction
programs, involving a specific set of
input data and initiating a specific
process or job.
TSOTime Sharing Option, The facility in z/OS that allows
users to interactively share computer time and
resources.
Virtual storage
An addressing scheme that allows external disk storage
to appear as main storage.
Volume
The storage space on DASD, tape, or
optical devices, which is identified by a volume label.
VSAMVirtual storage access method, An access method for
direct or sequential processing of fixed-length and
varying-length records on direct access devices. The
records in a VSAM data set or file can be organized in
logical sequence by a key field (key sequence), in the
physical sequence in which they are written on the data
set or file (entry-sequence), or by relative-record
number.
VTAM
Virtual telecommunications access method, A set of
programs that maintain control of the communication
between terminals and application programs running under
z/OS.
WLM
Workload management, A z/OS component that prioritizes
workloads and matches them with available resources.
z/OSA widely used operating system for IBM mainframe
computers that uses 64-bit central storage.
Features of z/OS:
