Is there a way to change the member variable in release code to linux while the program is running?

I wrote a program that solves some kind of optimization problem. I run it with ever lower thresholds and I think I hit some kind of barrier since my program cannot get better results. It works for about 5 days ...

However, I have code in the program that saves its data if it is better than the threshold. Since I am not interested in starting it in 5 days, I want to do this while the program is running, but unfortunately I did not compile it with -g (I use gcc). I am trying to change the threshold value to a higher value.

I managed to connect to it using gdb and see the stack frame. I am now inside the method and I want to access the "this" pointer to change the threshold parameter. I tried to check the values ​​at the function address, but nothing makes sense ... How do I know what "this" points to?

Thank.