The DB2 address spaces

DB2 requires several different address spaces.

Figure 1 shows these address spaces.
Figure 1. The DB2 address spaces
The CICS address space has connections to the DB2 subsystem. The DB2 subsystem contains the following address spaces: DSN1MSTR, DSN1DBM1, DSN1DIST, IRLMPROC, and DSN1SPAS.
Various tasks are performed in the different address spaces, as follows:
DSN1MSTR
for system services that perform a variety of system-related functions.
DSN1DBM1
for database services that manipulate most of the structures in user-created databases.
DSN1DIST
for distributed data facilities that provide support for remote requests.
IRLMPROC
for the internal resource lock manager (IRLM), which controls DB2 locking.
DSN1SPAS
for stored procedures, which provide an isolated execution environment for user-written SQL.