NAT0137 No object specified in RELEASE statement

Hi, Anyone know what this means? Our Natural batch on unix failed last night with this error.
Never seen this before. Any ideas?
No object specified in RELEASE statement.
Possible objects to be released are:
STACK - release all data items from the stack.
PARAMETERS - release all parameters built during the session.
SETS - release all FIND sets.
SET set name - release one specific FIND set.
Check program and correct error.

Have you SCANed all the modules in the batch to see which one(s) have a RELEASE statement? Assuming the batch job has been running with out problems for some time, I would look for RELEASE statements that are conditional. This would include RELEASE statements that are in objects that are conditionally executed and RELEASE statements that themselves are conditionally executed.