DB2 system objects

Unlike the DB2® data structures that users create and access, DB2 controls and accesses system objects.

DB2 has a comprehensive infrastructure that enables it to provide data integrity, performance, and the ability to recover user data. In addition, Parallel Sysplex® data sharing uses shared system objects.

DB2 catalog
DB2 maintains a set of tables that contain information about the data that DB2 controls. These tables are collectively known as the catalog.
DB2 directory
The DB2 directory contains information that DB2 uses during normal operation.
Active and archive logs
DB2 records all data changes and other significant events in a log.
Bootstrap data set
The bootstrap data set (BSDS) is a VSAM key-sequenced data set (KSDS). This KSDS contains information that is critical to DB2, such as the names of the logs. DB2 uses information in the BSDS for system restarts and for any activity that requires reading the log.
Buffer pools
Buffer pools are areas of virtual storage that temporarily store pages of table spaces or indexes.
Data definition control support database
The data definition control support (DDCS) database refers to a user-maintained collection of tables that are used by data definition control support to restrict the submission of specific DB2 DDL (data definition language) statements to selected application identifiers (plans or collections of packages).
The resource limit facility
The resource limit facility (sometimes abbreviated RLF) enables you to control the amount of processor resources that are used by SQL statements.
Work file database
Use the work file database as storage for processing SQL statements that require working space, such as that required for a sort.
Application processes and transactions
An application process involves running one or more programs. Different application processes might involve running different programs or running the same program at different times. When an application interacts with a DB2 database, a transaction begins.
Subsystem parameters
Subsystem parameters are settings that apply to a DB2 for z/OS subsystem. For example, the AUTH subsystem parameter controls whether DB2 checks authorizations. Many users colloquially refer to subsystem parameters as zparms.

Parent topic: DB2 for z/OS and SQL concepts

Related concepts:

DB2 Database objects overview