ESDS is one type of VSAM file. It does not support with COBOL, since it is possible accessing records through RBA only. Each record has its own RBA we can not predict it so it does not support in COBOL.
There are 2 reasons why ESDS supports more in CICS.
1. We normally use in cics vsam files like KSDS,RRDS and ESDS
2. The speciality with ESDS is it is entry sequenced, each transaction the record is added at the end of the file. Also, this file does not support any sorting on it.
3. RBA is stores as internal form for each record. So in cics we can read a record through RBA. This is faster and it takes less CPU time.
Because of the above reasons ESDS extensively used in CICS.