DB2� operates as a formal subsystem of z/OS� and works efficiently with other z/OS subsystems and components.
DB2 operates as a formal subsystem of z/OS. A subsystem is a secondary or subordinate system that is usually capable of operating independently of, or asynchronously with, a controlling system. A DB2 subsystem is a distinct instance of a relational DBMS. Its software controls the creation, organization, and modification of a database and the access to the data that the database stores.
z/OS processes are separated into regions that are called address spaces. DB2 for z/OS processes execute in several different address spaces, as indicated below.
- Database services
- ssnmDBM1 provides most database-related services. Most large storage areas reside above the 2 GB bar in the ssnmDBM1 address space. With 64-bit virtual addressing to access these storage areas, DB2 can scale to extremely large sizes.
- System services
- ssnmMSTR performs a variety of system-related functions.
- Distributed data facility
- ssnmDIST provides support for remote requests.
- IRLM (internal resource lock manager)
- IRLMPROC controls DB2 locking.
- WLM-established
- Zero to many address spaces for stored procedures and user-defined functions. WLM-established address spaces are handled in order of priority and are isolated from other stored procedures or user-defined functions that run in other address spaces.
- User address spaces
- At least one, possibly several, of the following types of user address spaces:
- TSO
- Batch
- CICS�
- IMS� dependent region
- IMS control region
- WebSphere�
DB2 works efficiently with other z/OS subsystems and components, such as the z/OS Security Server and the zSeries� Parallel Sysplex� environment.
DB2 utilities run in the z/OS batch or stored procedure environment. Applications that access DB2 resources can run within the same z/OS system in the CICS, IMS, TSO, WebSphere, stored procedure, or batch environments, or on other operating systems. These applications can access DB2 resources by using the client/server services of the DB2 Distributed Data Facility (DDF). IBM� provides attachment facilities to connect DB2 to each of these environments.
