s390-*-linux*
S/390 system running GNU/Linux for S/390.
s390x-*-linux*
zSeries system (64-bit) running GNU/Linux for zSeries.
s390x-ibm-tpf*
zSeries system (64-bit) running TPF. This platform is supported as cross-compilation target only.
[link|http://gcc.gnu.org/install/specific.html#s390x-ibm-tpf*|http://gcc.gnu.org/i...ml#s390x-ibm-tpf*]
thanx,
bill