ENTRY SGP records can be replaced by XREF SGP records and they can be up to 16k in size as opposed to 4k for ENTRY records
The records that are currently being used are E(SGP) records and they have alimit of 4k for the record size.
The message ACF0A016 is issued because the E(SGP) record has exceeded its maximum record size.
There is a replacement for E(SGP) records - X(SGP) records - which , withrulelong specified, can have a maximum size up to 16k. You will need RO54826 applied to be able to use 16k records.
There is a conversion utility called ACFESGP that will convert E(SGP) records to X(SGP) records - details can be found in the CA ACF2 for z/OS Reports and Utilities guide.
One further advantage of using X(SGP) instead of E(SGP) is that X(SGP) record entries can be masked - using include and exclude parameters - so that you can say something like add all entries that begin with abc but exclude those that begin abcd.
INSERT record1 INCLUDE(ABC-) EXCLUDE(ABCD-)