Exception occurs in Fortran

This scenario describes the behavior of an application that contains a Fortran and a PL/I routine. Refer to Figure 1 throughout the following discussion. In this scenario, a PL/I main routine invokes a Fortran subroutine. An exception occurs in the Fortran subroutine.

The actions taken follow the three Language Environment condition handling steps: enablement, condition, and termination imminent.

1. If an I/O error is detected on a Fortran I/O statement that contains an ERR or IOSTAT specifier, Fortran semantics take precedence. The exception is not signaled to the Language Environment condition handler.
2. In the enablement step, Fortran treats all exceptions as conditions. Processing continues with the condition handling step.
3. There is no user-written condition handler on the Fortran stack frame (because CEEHDLR cannot be called from a Fortran routine), and the condition is percolated.
4. If a user-written condition handler has been registered on the PL/I stack frame using CEEHDLR, it is given control. If it issues a resume, the condition handling step ends. Processing continues in the routine at the point where the resume cursor points.

   In this example, no user-written condition handler is registered for the condition, so the condition is percolated.

5. If an ON-unit has been established for the condition being processed on the PL/I stack frame, it is given control. If it issues a GOTO out-of-block, the condition handling step ends. Execution resumes at the label of the GOTO. In this example, no ON-unit is established for the condition, so the condition is percolated.
6. What happens next depends on whether the condition is promotable to the PL/I ERROR condition. The following can happen:
   • If the condition is not promotable to the PL/I ERROR condition, then the Language Environment default actions take place, as described in Table 1. Condition handling ends.
   • If the PL/I default action for the condition is to promote it to the PL/I ERROR condition, The condition is promoted, and another pass of the stack is made to look for ERROR ON-units or user-written condition handlers. If an ERROR ON-unit or user-written condition handler is found, it is invoked.
   • If either of the following occurs:
     • An ERROR ON-unit or user-written condition handler is found, but it does not issue a GOTO out of block or similar construct
     • No ERROR ON-unit or user-written condition handler is found
     then the ERROR condition is promoted to T_I_U (Termination Imminent due to an Unhandled condition). Condition handling now enters the termination imminent step. Because T_I_U maps to the PL/I FINISH condition, both FINISH ON-units and user-written condition handlers can be run if the stack frames in which they are established is reached.
   • If no condition handler moves the resume cursor and issues a resume, Language Environment terminates the thread.