Branching to a subspace

A server program branches to a subspace when it issues the BSG instruction with the ALET that corresponds to the desired subspace, and its primary and home address spaces are the same. The BSG instruction uses an ALET-qualified branch address to switch to the subspace. Use the ALET returned by ALESERV ADD.

The server program can use the BSG instruction to pass control to an application program which will run in the subspace. Alternately, the server program itself can begin running in the subspace. See Principles of Operation for details about coding the BSG instruction.

After issuing the BSG instruction, a program can reference the subspace while running in primary, secondary, or AR modes. The program runs in a subspace until it switches to:

Another subspace or full address space addressability, by issuing another BSG instruction
Another address space, by issuing a space-switching instruction.