zmmailboxdctl is not running

Just installed ZCS 7.2 on CentOS 6.3. All seemed to go well, except zmmailboxdctl won't start. I get the following in the /var/log/zimbra.log file:

Too small initial heap for new size specified
Error occurred during initialization of VM
Too small initial heap for new size specified
Error occurred during initialization of VM
Too small initial heap for new size specified
Error occurred during initialization of VM
Too small initial heap for new size specified
Error occurred during initialization of VM
Too small initial heap for new size specified
Error occurred during initialization of VM
Too small initial heap for new size specified
Error occurred during initialization of VM
Too small initial heap for new size specified
Error occurred during initialization of VM
Too small initial heap for new size specified


I'm assuming that a size parameter needs updating/tweaking, but where/how?

Alan