DSXchange

The source column for transformer is CLAIMAMOUNT(NVARCHAR(255)).
I am converting to StringToDecimal(CLAIMAMOUNT) of length 19 and scale 6.It is not throwing any error.I excepted warning in log since 255 will not fit into length 19 and scale 6.Could anybody provide input on this why it is not throwing any warning?

It "will not fit"? That depends entirely on what is inside the large string. Can you show us some specific examples of values you think should throw a warning?

Currently all the values in source are in the range of length 19 and scale 6.
Let us say I have value like 99999.....9 [Fill length 255] in source.

Question 1: In that case will DataStage will throw warning?

Question 2: Currently I do not have that scenario (99999.....9 [Fill length 255]). Due to this I am not getting a warning. If I have
a scenario like it will it throw an error? Please correct me if I am wrong.

Remove all doubt by trying it yourself, see what it does. Then let us know.