30.5.2 Stack allocation

When the -fstack flag is enabled, the compiler may automatically replace some heap allocations with stack allocations. This may improve performance because stack allocations are handled more efficiently than heap allocations. On some cases, -fstack may also cause slow down or memory extra retentions. In this last case, when compile using -fstack the program will consume more memory. Unfortunately, this is nasty phenomenon is unpredictable (it depends on the nature of the source file).