Introduction › Session Considerations › Program Currency

Program Currency

Determines Abend Trapping

When a task abends or when a program checks occurs, the setting of program currency determines whether or not the debugger traps the abend and transfers control to you.

DC/UCF and Debugger Currency

The DC/UCF system assigns currency on the basis of the most recent program to have been given control with #LINK or #XCTL program control services.

The debugger assigns currency according to these rules:

• If the address of the interrupt is contained in one of the programs defined to the debugger, this program is assigned debugger currency, and you are given control under the debugger
• If the address is not found in a debugged program, the debugger checks the current DC/UCF program to see whether it has been defined to the debugger:
  • If the current DC/UCF program has been defined to the debugger, this program is assigned debugger currency, and you gain control under the debugger
  • If the program has not been defined, no debugger currency is assigned, you do not gain control under the debugger, and the standard DC/UCF abend processing takes place

Sample Program Structure

The following examples illustrate how program currency can affect whether the DC/UCF system passes control to the debugger. Each of the examples is based on the sample program structure:

Sample Program Structure for Examples

Example 1

During the setup phase, you define Programs A, B, and C to the debugger. When the program is executing, a program check occurs in Program B.

These currencies are now in effect:

• The current DC/UCF program is Program A, the last program to have been given control by #LINK or #XCTL
• Debugger currency is assigned to Program B

You receive control under the debugger because Program B, one of the programs defined to the debugger, contains the address of the interrupt.

Example 2

During the setup phase, you define Program A to the debugger. When the program is executing, a program check occurs in Program B.

These currencies are now in effect:

• The current DC/UCF program is Program A, the last program to have been given control by #LINK or #XCTL
• Debugger currency is assigned to Program A

You receive control under the debugger because the current DC/UCF program has also been defined to the debugger.

Example 3

During the setup phase, you define Program C to the debugger. When the program is executing, a program check occurs in Program B.

These currencies are now in effect:

• The current DC/UCF program is Program A, the last program to have been given control by #LINK or #XCTL
• Debugger currency is not assigned, because the debugger cannot find the interrupt address in a known program and the current DC/UCF program is not defined to the debugger

You do not receive control under the debugger because no debugger currency can be set. The program abends without an interruption from the debugger, and the system issues a standard abend message.

Example 4

During the setup phase, you define Program A to the debugger. During execution, Program B branches into unknown storage and a program check occurs.

These currencies are now in effect:

• The current DC/UCF program is Program A, the last program to have been given control by #LINK or #XCTL
• Debugger currency is assigned to Program A

You receive control under the debugger because the current DC/UCF program has also been defined to the debugger.