The "Optimization" section of the "Configuration Parameters" has several optimizations related to removing zero initializations. If you disable these optimizations, it should generate initialization code consistently, regardless of which numeric values are used.
With the optimizations enabled, most initialization code is removed, except for non-zero values, or initializations that occur in "conditionally-executed subsystems" (e.g. enabled subsystems). The general idea is that many embedded systems zero-out RAM at power-on, making explicit zero-initialization redundant. However, these conditionally-executed subsystems may need to be reset independently of a power-on condition meaning that they are not redundant.
