Glossary

ACB

See Application Control Block.

ACBLIB

the data set that contains the DL/I Application Control Blocks. See also Application Control Block.

access descriptor

a SAS/ACCESS file that describes data that is managed by SAS, by a database management system, or by a PC-based software application such as Microsoft Excel, Lotus 1-2-3, or dBASE. After creating an access descriptor, you can use it as the basis for creating one or more view descriptors. See also view descriptor.

Application Control Block (ACB)

a DL/I control block that contains the combined information from the Database Descriptions (DBDs) and Program Specification Blocks (PSBs).

attach parameter list

a set of parameters that are passed to DL/I when the IMS engine or the IMS DATA step interface is executed in a DL/I environment. The parameters vary for each region type. Most parameters can be modified with SAS system options that are specified for the SAS/ACCESS interface to IMS.

Batch Message Processing region (BMP region)

a DL/I processing environment in IMS/ESA DB/DC subsystems and in CICS for running batch programs that access active online DL/I databases and message queues, as well as non-DL/I data sets. Database data sets are allocated to an online control region, not to the BMP region.

batch mode

a noninteractive method of running SAS programs by which a file (containing SAS statements along with any necessary operating system commands) is submitted to the batch queue of the operating environment for execution.

batch region

a DL/I processing environment for running batch mode jobs to access DL/I databases. Database data sets must be allocated to this region. A batch region is supervised by the DL/I batch control program.

BMP region

See Batch Message Processing region.

checkpoint

an identified point in a program’s execution that is used for restarting the program in case of failure.

checkpoint ID

an eight-byte value that is written to the DL/I log record to identify a program checkpoint.

command code

a special indicator that is used in a Segment Search Argument (SSA) to modify the type of call that is being issued. The most commonly used command code is the D code, which is used to issue a path call.

commit

the process that ends a transaction and that makes permanent any changes to the database that the user made during the transaction.

control region

a DL/I region that controls databases and terminals and schedules activities using these resources for online processing.

Data Language/I (DL/I)

the IBM database language for IMS/VS, CICS/OS/VS, CICS/DOS/VS, and DL/I DOS/VS systems.

data set

See SAS data set.

DATA step

in a SAS program, a group of statements that begins with a DATA statement and that ends with either a RUN statement, another DATA statement, a PROC statement, or the end of the job. The DATA step enables you to read raw data or other SAS data sets and to create SAS data sets.

DATA step view

a type of SAS data set that consists of a stored DATA step program. A DATA step view contains a definition of data that is stored elsewhere; the view does not contain the physical data. The view's input data can come from one or more sources, including external files and other SAS data sets. Because a DATA step view only reads (opens for input) other files, you cannot update the view's underlying data.

data type (type)

an attribute of every column in a table or database, indicating the type of data in the column and how much physical storage it occupies.

data value

a unit of character, numeric, or alphanumeric information that is stored as a single item in a data record.

data view

See SAS data view.

database

an organized collection of related data. A database usually contains named files, named objects, or other named entities such as tables, views, and indexes.

Database Administrator (DBA)

the person who is responsible for developing and maintaining database management systems at a computer site.

Database Description (DBD)

a DL/I control block that defines the hierarchical data structure and the physical characteristics of a database to DL/I.

database management system (DBMS)

a software application that enables you to create and manipulate data that is stored in the form of databases. See also hierarchical structure, relational database management system.

Database Recovery Control (DBRC)

an IMS facility that controls the restoration of databases after a system failure. DBRC also supports data sharing among IMS/ESA subsystems.

DBA

See Database Administrator.

DBB region

a DL/I batch processing environment for running programs that can access DL/I databases as well as non-DL/I data sets. In a DBB region, DL/I accesses the ACBLIB in order to obtain control block information.

DBD

See Database Description.

DBDGEN

the utility procedure that generates Database Descriptions (DBDs).

DBDLIB

a data set that contains Database Descriptions (DBDs).

DBMS

See database management system.

DBRC

See Database Recovery Control.

dependent segment

a segment that has a parent segment. The data in a dependent segment relies on the parent segment and on all higher segments for complete identification and qualification. See also segment.

DL/I

See Data Language/I.

DL/I call

a request made by the IMS-DL/I engine to DL/I to access one or more segments of a database or message queue, or to perform some system function.

DLI region

a DL/I batch processing environment for running programs that can access DL/I databases as well as non-DL/I data sets. No access to message queues is possible. In a DLI region, DL/I accesses the DBDLIB and PSBLIB for control block information.

engine (SAS engine)

a component of SAS software that reads from or writes to a file. Various engines enable SAS to access different types of file formats.

feedback data

the data that is returned to the IMS engine (usually in the PCB mask) after a DL/I call has been issued.

field

the smallest logical unit of data in a file.

Get call

a DL/I call that retrieves one or more segments so that the contents of the segments can be read by the IMS engine.

hierarchical database

a database that is organized as a tree structure of segments. A DL/I database has a hierarchical data structure.

hierarchical sequence

the standard processing sequence for segments of a database record. The sequence is basically top-to-bottom, front-to-back, and left-to-right.

hierarchical structure

an arrangement of data in which records occur at distinct levels, with different types of information at each level. Records are related to other records as ancestors, descendants, siblings, and so on.

I/O area

a data structure in which the IMS-DL/I engine holds retrieved segments for processing or output.

I/O PCB

See I/O Program Communication Block.

I/O Program Communication Block (I/O PCB)

a type of DL/I control block that communicates information about non-database access requests. See also Program Communication Block.

IMS/ESA

Information Management System/Enterprise System Architecture. IMS/ESA is an IBM database management system that uses the DL/I database language.

IMS/ESA Resource Lock Manager (IRLM)

a facility for ensuring database integrity among multiple DL/I subsystems.

index

See SAS index.

interactive line mode (line mode)

a method of running SAS programs in which you enter one line of a SAS program at a time at the SAS session prompt. SAS processes each line immediately after you press the ENTER or RETURN key. Procedure output and informative messages are returned directly to your display device.

interface view engine

a type of SAS engine that SAS/ACCESS software uses to retrieve data from files that have been formatted by another vendor's software. Each SAS/ACCESS interface has its own interface view engine, which reads the interface product data and returns the data in a form that SAS can understand (that is, in a SAS data set). See also engine.

IRLM

See IMS/ESA Resource Lock Manager.

key field

See sequence field.

library member

any of several types of SAS file in a SAS library. A library member can be a data set, a view, a catalog, a stored program, or an access descriptor.

library reference

See libref.

libref (library reference)

a SAS name that is associated with the location of a SAS library. For example, in the name MYLIB.MYFILE, MYLIB is the libref, and MYFILE is a file in the SAS library. See also SAS library.

line mode

See interactive line mode.

logical database

a collection of database segments from one or more physical databases. A logical database enables the IMS-DL/I engine to view a database structure that is different from the physical structure.

member name

a name that is assigned to a SAS file in a SAS library. See also member type.

member type

a SAS name that identifies the type of information that is stored in a SAS file. Member types include ACCESS, AUDIT, DMBD, DATA, CATALOG, FDB, INDEX, ITEMSTOR, MDDB, PROGRAM, UTILITY, and VIEW.

missing value

a type of value for a variable that contains no data for a particular row or column. By default, SAS writes a missing numeric value as a single period and a missing character value as a blank space.

noninteractive mode (noninteractive processing)

a method of running SAS programs in which you prepare a file of SAS statements and submit the program to the operating system. The program runs immediately and comprises your current session.

noninteractive processing

See noninteractive mode.

observation

a row in a SAS data set. All of the data values in an observation are associated with a single entity such as a customer or a state. Each observation contains either one data value or a missing-value indicator for each variable.

online access region

a DL/I processing environment for running batch programs that can access active online DL/I databases. The only type of online access region that the SAS/ACCESS interface to IMS supports is the BMP region.

parent

in a hierarchical database, a segment or node that has one or more subordinate segments, or children. The branching of parents and children form a tree structure in which each level obtains identifying and qualifying features from the parent level above it.

path

the route through a hierarchical file system that leads to a particular file or directory.

path call

a DL/I call to a database that returns multiple segments from a hierarchical path.

PCB

See Program Communication Block.

PCB mask

a data structure to which DL/I returns information about the DL/I calls that an application issues.

physical database

a collection of database segments in a specified hierarchical structure. These segments are organized according to a particular DL/I access method.

PROC SQL view

a SAS data set that is created by the SQL procedure. A PROC SQL view contains no data. Instead, it stores information that enables it to read data values from other files, which can include SAS data files, SAS/ACCESS views, DATA step views, or other PROC SQL views. The output of a PROC SQL view can be either a subset or a superset of one or more files. See also SAS data view.

PROC step

a group of SAS statements that call and execute a SAS procedure. A PROC step usually takes a SAS data set as input.

Program Communication Block (PCB)

a DL/I control block that defines either a message queue or the part of a database that can be accessed by the IMS-DL/I engine. A PCB is part of a Program Specification Block (PSB).

Program Specification Block (PSB)

DL/I control block that defines the DL/I resources that are used by the IMS-DL/I engine. Each database that the IMS-DL/I engine uses is defined by a separate Program Communication Block (PCB) within the PSB.

program view

the part of a database that the IMS-DL/I engine can access. The Program Communication Block (PCB) establishes the program view.

PSB

See Program Specification Block.

PSBGEN

the process that generates Program Specification Blocks (PSBs

PSBLIB

the data set that contains the Program Specification Blocks (PSBs).

qualified call

a DL/I call that specifies at least one Segment Search Argument (SSA). See also Segment Search Argument.

qualified SSA

a Segment Search Argument that contains one or more qualification statements to specify search criteria for locating particular segment occurrences. See also Segment Search Argument.

random access

an access mode that is used by the IMS engine or by the IMS DATA step interface. This access mode is used when a WHERE statement is specified from which the engine can generate Segment Search Arguments. In the SAS/ACCESS interface to IMS-DL/I, the distinction between sequential access and random access differs from that of some other programming languages.

RDBMS

See relational database management system.

Read integrity

a characteristic of database management systems in which database access is controlled so that two programs cannot access a record simultaneously if one of the programs is requesting Update access. Read integrity guarantees that the data is always current when Read access is granted.

region type

the kind of DL/I processing environment. The IMS engine uses two categories of region types: batch regions (DLI or DBB) and online access regions (BMP).

relational database management system (RDBMS)

a database management system that organizes and accesses data according to relationships between data items. The main characteristic of a relational database management system is the two-dimensional table. Examples of relational database management systems are DB2, Oracle, Sybase, and Microsoft SQL Server.

restart

the process of resuming an interrupted program without repeating completed transactions.

restricted option

a SAS system option that has been installed at a site with a default setting that cannot be overridden by applications programmers.

return code

a numeric value that indicates whether a request was successful. A return code can also indicate a specific error or warning.

root segment

the highest-level segment in a database.

SAS data file

a type of SAS data set that contains data values as well as descriptor information that is associated with the data. The descriptor information includes information such as the data types and lengths of the variables, as well as the name of the engine that was used to create the data. See also SAS data set, SAS data view.

SAS data set (data set)

a file whose contents are in one of the native SAS file formats. There are two types of SAS data sets: SAS data files and SAS data views.

SAS data view (data view)

a type of SAS data set that retrieves data values from other files. A SAS data view contains only descriptor information such as the data types and lengths of the variables (columns) plus other information that is required for retrieving data values from other SAS data sets or from files that are stored in other software vendors' file formats.

SAS engine

See engine.

SAS file

a specially structured file that is created, organized, and maintained by SAS. A SAS file can be a SAS data set, a catalog, a stored program, an access descriptor, a utility file, a multidimensional database file, a financial database file, a data mining database file, or an item store file.

SAS index (index)

a component of a SAS data set that enables SAS to access observations in the SAS data set quickly and efficiently. The purpose of SAS indexes is to optimize WHERE-clause processing and to facilitate BY-group processing.

SAS library

one or more files that are defined, recognized, and accessible by SAS, and that are referenced and stored as a unit. Each file is a member of the library.

SAS variable (variable)

a column in a SAS data set or in a SAS data view. The data values for each variable describe a single characteristic for all observations (rows).

SAS/ACCESS view

a type of file that retrieves data values from files that are stored in other software vendors' file formats. You use the ACCESS procedure of SAS/ACCESS software to create SAS/ACCESS views. See also view descriptor.

search field

a field that is defined to DL/I in the Database Description (DBD) and which can be used to search for particular segments. A search field does not uniquely identify the segment.

segment

in a DL/I database, a grouping of related data items in a database structure. The segment is the unit of data that can be accessed by the IMS engine or by the IMS DATA step interface.

segment level

the relative distance of a particular segment from the root segment along a hierarchical path. The segment level is usually represented numerically, with the root segment at level 1 and its immediate dependents at level 2.

segment occurrence

in a DL/I database, a specific instance in a set of segments that have the same segment type.

Segment Search Argument (SSA)

the formatted search criteria that are passed to DL/I in order to identify a particular segment or group of segments to be processed. Multiple SSAs can be specified in one DL/I call.

segment type

in a DL/I database, a category of related data elements. There can be multiple segment occurrences for a particular segment type.

sensitive segment

a segment in a DL/I database that the IMS engine or the IMS DATA step interface can access. A segment is defined as sensitive for a particular program in the Program Specification Block (PSB).

sequence field (key field)

a field that identifies and provides access to segments in a database. It contains the record's key, which is located in the same position in each record of a key-sequenced data set.

sibling

in a hierarchical database, any of two or more segments or records that have the same parent segment or record.

SQL

See Structured Query Language.

SSA

See Segment Search Argument.

status code

a two-byte indicator field that DL/I returns to indicate the relative success of an attempted call.

Structured Query Language (SQL)

a standardized, high-level query language that is used in relational database management systems to create and manipulate objects in a database management system. SAS implements SQL through the SQL procedure.

subsystem

a complete DL/I configuration, including the DL/I region controller and service modules, the DL/I databases, and the IMS engine.

synchronization point

a time at which a) all update commands that have been successfully executed and applied since the previous synchronization point was established are committed to the database and b) all DL/I resources that have been held since the previous synchronization point was established are released. Synchronization points are established by issuing CHKP calls. By default, the SAS IMS engine generates and submits a CHKP call at the end of a PROC step or DATA step, whereas the DATA step interface to IMS generates and submits explicit CHKP calls as coded by the application logic. Synchronization points can be used to resume the processing of an interrupted job. See also commit.

twins

segments that represent multiple occurrences of the same segment type under a single parent.

type

See data type.

undefined field

a field that is not defined to DL/I in a Database Description (DBD). An undefined field is neither a sequence field nor a search field. The segment cannot be accessed by specifying this field to DL/I.

unqualified call

a DL/I call that contains no Segment Search Argument (SSA). See also Segment Search Argument.

unqualified SSA

a Segment Search Argument that specifies a segment type only. See also Segment Search Argument.

update call

a DL/I call that signals the intent to alter (modify, delete, or add) information in the database.

Update integrity

a characteristic of a database management system in which database access is controlled so that two programs cannot access a record simultaneously if both programs are requesting Update access. Update integrity guarantees that data is always current when Update access is granted. However, it does not guarantee that data is always current when Read access is granted.

variable

See SAS variable.

view descriptor

a SAS/ACCESS file that defines part or all of the DBMS data that is described by an access descriptor. See also access descriptor.