REXX External Assembler API › Environmental Considerations

Environmental Considerations

In the TSO/E implementation of REXX, each user has their own address space.

Under TSO/E, most programs execute unauthorized. The programs are loaded from unauthorized libraries, and cannot perform authorized functions.

Under Tivoli NetView, multiple users share the one address space. Work for different users is processed under different tasks. Also, the address space itself and all tasks in the address space execute in an APF-authorized environment.

Under CA NetMaster, multiple users share one address space and the environment is APF-authorized. When writing REXX external interface programs, consider the following points:

• All programs must be loaded from an APF-authorized library. APF libraries are restricted for update by the security system.
• The interface programs can perform functions that can damage the address space or system. Thus, it is imperative that they are carefully checked.
• User-written external interface programs must be registered before they can be used. This additional step prevents accidental execution of programs in an APF-authorized environment.
• Update access to the REXX source libraries available to a region should be restricted.