Getting a different BLE event depending on the size of the write request

Hello,

i'm using CySmart along a software I wrote for the PSoC 4 and I have the following problem:

In my StackEventHandler function, when the message I'm trying to write to a certain custom characteristic has a certain number of bytes or less, I get a CYBLE_EVT_GATTS_WRITE_REQ event.

When the message has a lot of bytes (around 20+) I get CYBLE_EVT_GATTS_EXEC_WRITE_REQ. 

In other words, I can proccess the data prior to writing only if it is less than a certain number of bytes, if the number of bytes is bigger than this threshold, it gets written directly to the characteristic. Why is that?