ps3: Improve a size determination in five functions

[SF Markus Elfring]

> Some observations:
> 
>  o Your patch fixes no bug nor replaces any depreciated feature.

How do you think about information from the section “14) Allocating memory”
in the document “coding-style.rst” for the shown source code transformation?


>  o There will be no functional change; …

Yes. - The suggested adjustment should work in this way generally.

Regards,
Markus