Recompilation of glibc is not necessarily required, but it is recommended. It was
compiled using a more buggy compiler than the one you have installed; as such, it
is an absolute false economy not to recompile it. Personally, after every update
of a particularly important package (kernel headers, glibc, gcc, binutils, kernel
etc. etc.) I do the following:

Code:
emerge -e system
emerge -e system
emerge -e world
emerge -e world

The first command ensures my toolchain is in order; the second ensures it's been
compiled with a clean and current toolchain; the third re compiles all my
packages with a clean and current toolchain; the fourth ensures that all my
packages are compiled against packages compiled with a clean and current
toolchain.

pa mislim shto da ne,ali,dzaba joj inteligencija ako oduzima isto vremena kao i emerge -e system..