NPTL in RH9 vs RHEL3

I run SAPDB on Redhat9, and am trying to migrate to RHEL3.  It is well known
that SAPDB requires the LD_ASSUME_KERNEL=2.2.5 to run on Redhat.  Using this
settings, I have run SAPDB on Redhat9 with great success.  The same tactic
on RHEL3 results in a much slower, and less stable database.

It seems that on Redhat9, the LD_ASSUME_KERNEL=2.2.5 disables floating
stacks, but somehow leaves NPTL operational (as opposed to toggling
linuxthreads).  The getconf command indicates this overtly:

[RH9]# getconf GNU_LIBPTHREAD_VERSION
NPTL 0.29

On RHEL3, however, setting LD_ASSUME_KERNEL=2.2.5 results in nptl being
disabled in favor of linuxthreads:

[RHEL3]# getconf GNU_LIBPTHREAD_VERSION
linuxthreads-0.10



I also see significant differences when running top on the machines.  On the
RH9 box, the number of SAPDB processes remains minimal.  One the RHEL3 box,
I see dozens of SAPDB processes.  Java behaves similarly.



My questions are:

1) whether or not there is something special about the RH9 glibc or kernels
that allow nptl to function despite the LD_ASSUME_KERNEL=2.2.5 setting?

2) Is it possible to recompile glibc2.3.2-95.6 for RHEL3 such that it
behaves in the same way?

3) Is there a more subtle way to achieve this?  Can I discretely disable
floating stacks without using the LD_ASSUME_KERNEL setting?  Or could I use
a version of glibc that has no support for linuxthreads at all, or at least
is more reluctant to resort to linux threads?



thanks