Cannot link openssl and openssh against /usr/lib/libz.a on my 5.1 system.

Main goal: one shared, threadsafe libz.a for all my apps.
Since it is used by quite a few apps, I prefer early binding over
runtime binding, but I don't want a private copy for every app nor
static linking. AIX 5.1 eats up enough RAM...

Since zlib-1.1.4 don't know how to build a shared lib on AIX by default
I did it myself on 4.3.3 without any problems:
Compiled with cc_r and forced the threadsafe flags durig "./configure".
extracted all archive members to a temp dir with
"ar -x ../libz.a" and linked the shared lib with a simple:
"cc_r -G -O -qarch=com `ls *.o` -o libz.a"
a "dump -Ht libz.a" shows all objects on my lib.

On AIX 5.1 the libz.a has a single member "libz.so.1"
No headers for using this lib in the system.
lslpp -w /usr/lib/libz.a gives no results.
My own libz from 4.3.3 works on 5.1 as expected, but I don't like to
overwrite a system lib.
For stylistic reasons, using the system lib is the preferred way.

Any recommendations?
Or is the Linux affinity AIX5L the same shared lib hell like major Linux
distros?

---
Uli