oci-21500 error on AIX 6.1

we use an application executing different processesthose processes are pro*C processes
standalone processes work fine but multithread processes generate this erreur:

OCI-21500: internal error code, arguments: [KGHFRE3], [0x110693A80], [], [], [], [], [], []
OCI-21500: internal error code, arguments: [17099], [], [], [], [], [], [], []
**** Recursive heap error: KGHFRE3 addr=110693a80, ds=110694668
***** Dump of memory around addr 110693a80:
110692A80 00000000 00000000 00000000 00000000  [................]
        Repeat 68 times
110692ED0 00000000 00000000 10B38F00 00000841  [...............A]
110692EE0 00000001 106926E8 00000001 104ACED0  [.....i&......J..]
110692EF0 00000001 104DD3B8 00000001 104DCF08  [.....M.......M..]
110692F00 10B38F00 00000819 00000000 00000000  [................]
110692F10 09000000 06988F28 849A8F00 00000802  [.......(........]
110692F20 00000000 00000000 00000001 104DD398  [.............M..]
110692F30 00000001 104DCF98 00000001 104DD4B8  [.....M.......M..]
110692F40 B09A8F00 0000055A 00000000 00000000  [.......Z........]
110692F50 00000001 104DD7C8 00000001 104DD7C8  [.....M.......M..]
110692F60 00000000 00000000 00000000 00000000  [................]
        Repeat 82 times
110693490 00000000 00000000 809A8F00 00000092  [................]