15.4.4 Interpreting the Report

The stack-usage report is written:

Directly to standard error (either on terminal for command-line execution or in the MPLAB X output window).
To the map file.

The same information is available in both places, but the map file can serve as a record for later review.

The report contains:

The largest stack usage that could be determined by static analysis.
A list of reasons that the maximum stack usage couldn't be determined, such as recursion or variable adjustment of the stack.
A list of disjoint and/or interrupt handler functions, which are not called directly by the main flow of the program.

To determine the appropriate stack size for your application:

First, start with the initial value from the reset-handler call graph. In this example, the report shows 72 bytes required for the reset-handler call graph.

Stack Usage Report

============= STACK USAGE GUIDANCE =============
In the call graph beginning at Reset_Handler,
72 bytes of stack are required.

Second, add the listed stack allowances based on the system-level, runtime behavior of your application.

Stack Usage Report

However, the following cautions exists:
1. The following functions cannot be connected to the main call graph.
This is usually caused by some indirection:
frame_dummy uses 8 bytes
Dummy_Handler uses 0 bytes
__libc_init_array uses 40 bytes
You must add stack allowances for those functions.
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Third, add stack allowances for your Interrupt handlers (interrupt service routines) as described in the following section.