You can change the host command environment either from the default environment (REXXCICS) or from whatever environment was previously established. To change the host command environment, use the ADDRESS instruction followed by the name of an environment.
When an ADDRESS instruction includes both the name of the host command environment and a command, only that command is sent to the specified environment. After the command is complete the former host command environment becomes active again.
When an ADDRESS instruction includes only the name of the host command environment, all commands issued afterward within that program are processed as that environment's commands.
This ADDRESS instruction affects only the host command environment of the program that uses the instruction. If a program calls an external routine, the host command environment is the default environment regardless of the host command environment of the calling program. Upon return to the original program, the host command environment that the ADDRESS instruction previously established is resumed.