Is there a command like pstree for libraries?

I need to determine whether a library named libunaSA.so is being called directly by the process or by another library called libtoki2.so. I guess what I'm looking for is a pstree for libraries. The system is running RHEL 5.3 Beta.

This output shows the two libraries in the process map

# grep -e toki -e una /proc/2335/maps
0043f000-004ad000 r-xp 00000000 08:02 543465     /usr/lib/libtoki2.so
004ad000-004c5000 rwxp 0006d000 08:02 543465     /usr/lib/libtoki2.so
01185000-01397000 r-xp 00000000 08:02 543503     /usr/lib/libunaSA.so
01397000-013dc000 rwxp 00211000 08:02 543503     /usr/lib/libunaSA.so

This output shows that only the libtoki2.so library is in the current cache

# ldconfig -p | grep -e una -e toki
libtoki2.so (libc6) => /usr/lib/libtoki2.so
libtoki.so.4.4.1 (libc6) => /usr/lib/libtoki.so.4.4.1
libtoki.so.2 (libc6) => /usr/lib/libtoki.so.2

I attached strace to the running process but it doesn't provide much output

# strace -p 2335
Process 2335 attached - interrupt to quit
futex(0xb7ef5bd8, FUTEX_WAIT, 2336, NULL

Here's the output to ldd for each library

# ldd /usr/lib/libtoki2.so
        linux-gate.so.1 =>  (0x00a0a000)
        libdl.so.2 => /lib/libdl.so.2 (0x001bd000)
        libstdc++-libc6.2-2.so.3 => /usr/lib/libstdc++-libc6.2-2.so.3 (0x00f3f000)
        libm.so.6 => /lib/libm.so.6 (0x00b27000)
        libc.so.6 => /lib/libc.so.6 (0x0043d000)
        /lib/ld-linux.so.2 (0x00742000)
        libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00110000)
# ldd /usr/lib/libunaSA.so
        linux-gate.so.1 =>  (0x00244000)
        libpthread.so.0 => /lib/libpthread.so.0 (0x00baf000)
        libdl.so.2 => /lib/libdl.so.2 (0x007fa000)
        libstdc++-libc6.2-2.so.3 => /usr/lib/libstdc++-libc6.2-2.so.3 (0x009ce000)
        libm.so.6 => /lib/libm.so.6 (0x00c96000)
        libc.so.6 => /lib/libc.so.6 (0x004a2000)
        /lib/ld-linux.so.2 (0x00742000)
        libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00a9f000)