Decfloat error working with int128 in UDR

[AlexPeshkoff]

An issue was reported to me privately.

On attempt to return really big int128 (42540766452641154071740215577757643572) from UDR function an error is raised:

Unsuccessful execution caused by system error that does not preclude successful execution of subsequent statements.
Decimal float invalid operation.  An indeterminant error occurred during an operation.
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SQLCODE: -901
SQLSTATE: 22000
GDSCODE: 335545141