Well, I went back and checked. zlib-devel is installed. When I look at the config.log file it does show that zlib is included:
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/u
sr/share/info --with-bugurl=
http://bugzilla.redhat.com/bugzilla --enable-bootstr
ap --enable-shared --enable-threads=posix --enable-checking=release
--with-syste
m-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-
object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=
gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --en
able-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/ja
va/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tun
e=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
But i don't see a config parameter that lets me set it.