Why ESDS Files Extensively Used in CICS

ESDS is one type of VSAM file. It does not support in COBOL. Since the records can be accessed using RBA only. Each record has its own RBA we can not predict it so it does not support in COBOL.

There are 3 reasons why ESDS supports more in CICS.

In CICS, we normally use VSAM files like KSDS, RRDS, and ESDS
The specialty with ESDS is it is entry-sequenced, and for each transaction, the record will add at the end of the file. Also, this file does not support any sorting on it.
RBA stores as an 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.