This error indicates that the oracle server process is unable to allocate more memory from the operating system.This memory consists of the PGA
This could be caused by your process itself, like your process is just requesting too much memory, or some other reasons cause the operating system memory to be depleted, like a too big SGA or too many processes to be accomadated for the systems virtual memory (physical memory + swap space).
To resolve this error check the following:
1) Is there still sufficient memory available?
2) Is there an operating system limit set?
3) Is there an oracle limit set?
4) Which process is requesting too much memory?
5) How to collect information on what the process is actually doing?
References : Metalink Note 233869.1