CLI automatically replenishes the response buffer(s). That is, the Teradata Database application program may call DBCHCL for the Fetch function repeatedly. The response buffer(s) may or may not be large enough to hold all the parcels in the response, but the application program can draw on them as if they are.
If the application program calls DBCHCL for the Rewind function, the pointer that moves back to the first parcel is a pointer in the response stored on a spool file in the Teradata Database, not a pointer in the response stored in the response buffer(s). Therefore, if rewinding may take place, it is important to operate with Keep Response set to Y, even if the whole response can fit in the response buffer(s).