DRL CALLSS (octal 30) - internal call to another subsystem.

Usage:

drl    callss
ascii  1,name

Where:

name: is the four character ASCII subsystem name.

Description:

The current (calling) subsystem is swapped out to be resumed later when a POPUP primitive of the called subsystem is executed. Internal calls may not be more than three levels deep; that is, nesting to more than three levels is not allowed.

The called subsystem may be any subsystem known to TSS (one with a program descriptor in the communication region). "name" is the subsystem name as recorded in the descriptor.

When the DRL CALLSS is followed by a DRL RETURN, the calling program is not swapped, but instead is killed and the nesting level is not increased.