ORA-04030: out of process memory when trying to allocate 8320 bytes (kxs-heap-c,temporary memory)

Hello,
We're getting the following error message:

ORA-04030: out of process memory when trying to allocate 8320 bytes (kxs-heap-c,temporary memory)

Please, how can we gather more information for finding out what's the root cause?

For example, could it be an insufficient value for PGA_AGREGATE_TARGET?
But if in 11g with have it set to 0 how can we query the actual value being dynamically/automatically used?

The instance is 11g running on Solaris 10 U10 (147440-12) zone with memory resource controls enabled but no significant paging is happening.

Thanks in advance,
Carlos.