Looking at the Call/Return Stack

Using the tb Command

Use the tb command to display a traceback of the call/return stack in the debugger output area.

The tb command numbers each frame in the stack using the notation `main(n), where n increases in the direction of the most recent frame. The following example illustrates this notation which was displayed after stepping to line 33 of the sample program average:

tb
`main(4):   Stopped at: \\average\print_average\33
`main(3):   Called from: \\average\main\44 (0000203C)
`main(2):   Called from: _start+0068 (80041D9C)
`main:      Called from: $START$+0094 (0000192C)

Using the environment Command

To move up and down the call/return stack to view the associated source code, enter the environment command. Use the notation `env(-1) to represent the caller of the current routine, as shown in the following example:

environment `env(-1)

After you enter the preceding command, you can easily examine the program data local to the routine shown in the source file display area.

To move down the stack, enter the following command:

environment `env(+1)

To return to the current point of execution, regardless of the source currently displayed, enter the following command:

environment `run

For details on the `env and `run notation, see “Frame Block Qualified Names ”. For a description of the HP/DDE concept of environment, see “Understanding Blocks and Environments”.