RE: Byte Alignment question with Change User Space Attributes API(QUSCUSAT) -- RPG400-L

One more question. When dealing with a key that needs the 3 byte filler such as the auto-extend.

Should the data length field of the input record be 1 or 4???


It depends on the API, and what it's going to use that length field for.

For this particular API, it says the following in the V5R2 information center:

  Length of data. The length of the new user space attribute value. The
     length of data field is used to get addressability to the next
     attribute record.

So that means that what the API is going to do with that length field is use it to determine where (what address in memory) the next input record is located at.

That being the case, you want it to move 4 bytes further in memory to find the next input record, because your filler field puts it 4 bytes later in memory instead of one.

I think you could use 4 even if it should be 1 since the manual says "If you specify a length of data that is longer than the key field's defined data length, the data will be truncated at the right. No error message will be returned".

And you can see why the API does that -- if it didn't, there'd be no way to skip over the padding.

This leads me to think 1 is correct, but the actual amount of space allocated for "data" is 4; even if this particular key doesn't use it all.

No, 4 is correct. If you had another record after it in memory, and you specified 1, it would calculate the wrong address for the next field.

Hope that helps...

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