HP-48G local variables within subroutine

[Boub65]

Hello and thanks for the examples.
My question is how can I use a local variable to do intermediate calculations within a subroutine that is NOT arguments transmitted to the subroutine NOR global variables.
For example I want to put a * b in "local variable" local_c to use it later in the subroutine.
Example :
《 -> a b 《 a b * 'local_c' STO then use local_c in this subtoutine... 》》

The scope of the local variable local_c would be restricted to the subroutine and we would not find it in the global variables (using VAR) after the subroutine ends. aka LSTO in Free42.
I hope I am clear enought?