Dynamically allocated new virtual shared memory segment repeatdly

Since a long time we have some troubles with Shared Memory segments assigned by the engine. When we run an onstat - g seg, this one shows that is always assigning new segments and it seems that they never release them, because sometimes appears the following error: [ENOMEM][12]: out of available data space, check system memory parameters (e.g. MAXMEM) How can we know the process these segments are generating? How can we release them, in case we could do it, without shut down the base? Thanks in advance