Final answer:
The Distributed Data Facility (DDF) in DB2 is used for communication with other DB2 subsystems, enabling distributed requests and data exchange.
Step-by-step explanation:
The DB2 address space used to communicate with other DB2 subsystems is the Distributed Data Facility (DDF). The DDF enables network communications and the processing of distributed requests. It allows DB2 to communicate and exchange data with remote clients and other DB2 databases.
The other address spaces mentioned, such as Lock Manager Services, Database Services, and System Services, have their specific roles within the DB2 environment but are not primarily responsible for communication with other subsystems.