Allocate: To designate the space or area for (a file, dataset, or member).
American Standard Code for Information Interchange (ASCII): A standard eight bit character set.
Binary: The language of computers. Values of zero and one are represented by the absence or presence, respectively, of electrical current in a circuit. One of these representations is a Binary dIgiT, or one bit .
Bit: A single binary digit.
Byte: A series of (usually) eight bits. An eight bit byte allows for representations of decimal values between zero and 255. For example, 11010110 is equivalent to the decimal value 214. Conversion from bina
ry to decimal is accomplished by, starting from right to left, multiplying the value of the digit by two to the power of its position relative to flush right and summing the results:
| 1 ´27 128 |
+ | 1 ´26 64 |
+ | 0 ´25 0 |
+ | 1 ´24 16 |
+ | 0 ´23 0 |
+ | 1 ´22 4 |
+ | 1 ´21 2 |
+ | 0 ´20 0 |
= | 214 |
Central Processing Unit (CPU): The "brain" of the computer. The computer element that is responsible for carrying out the primary processing functions.
Data Set: Any collection of related data. A data set can be partitioned (PDS) to contain multiple members, or may be a single "file cabinet" in which to store data.
Directory: A collection of files. Similar to a Partitioned Data Set (PDS).
File: A collection of records of data. The information you are reading now exists within a file, which exists within a directory.
Graphical User Interface (GUI): A user interface that allows for data manipulation via graphics, as opposed to a text-based system, such as MS-DOS©.
Interactive System Productivity Facility (ISPF): A menu-driven, full screen interface to the most commonly accessed TSO features. It includes facilities to edit, browse, and manage data and programs.
Job Control Language (JCL): The language used by the MVS mainframe to execute the various jobs required by the user.
Library: A collection of files. Also referred to as a Partitioned Data Set, or a directory.
Logical Record Length (LRL or LRECL): The length of an actual individual record in a file; how individual records are logically designed to satisfy data needs.
Member: A single entry in an MVS Partitioned Data Set (PDS). A fully qualified member name includes the name of the PDS outside parentheses and the member name within the parentheses: BA0145.SAMPLE.PROGRAMS(
SAMPLE1) The highest level qualifier , BA0145, is the same as the owner's Logon ID. The second and third level qualifiers, SAMPLE and PROGRAMS are used to provide a meaningful identification for the data set. There can be more than three levels of PDS name qualifiers but the total number of characters, including periods, is limited to 44 characters or fewer. The member name (the actual file being edited), SAMPLE1, is contained within parentheses. The member name must be 8 characters o
r fewer.
Multiple Virtual Storage (MVS): IBM's operating system for their 390 Series mainframes.
Nibble: Four bits, or ½ of a byte.
Partition: To divide, either physically or logically, into two or more pieces.
Partitioned Data Set (PDS): A collection of data known as members. All members of a PDS must have the same logical record length. A PDS member is identified by at
least 4 levels of qualifiers in the name. The first three qualifiers identify the PDS. Qualifiers are separated by periods within the name. Has some similarity to a directory in personal computer systems and is often re
ferred to as a library.
PROC (Procedure): Collection of JCL steps that can be executed together, as if it were a program.
Record: An "entry" in a file. Each term in this definition file can be thought of as a record.
Time Sharing Option (TSO): A multi-user environment for the IBM MVS mainframe operating system. TSO divides available CPU time and allocates the slices to users. Since the time slices are very short, and the system cycles through
the requesting users are very quick, it appears as if they have simultaneous access.