Record Overhead

Record overhead refers to bytes associated with each record that are used internally by the file system and are not available when a record is read or written. Knowing the record overhead helps when estimating the storage requirements for an application. Although the overhead bytes exist on the storage media, do not include them when specifying the record length with the RECL specifier in an OPEN statement.

The various record types each require a different number of bytes for record overhead, as described in the table below:

Record Type	File Organization	Record Overhead
Fixed-length	Sequential	None.
Fixed-length	Relative	None if the -vms option was omitted. One byte if the -vms option was specified.
Variable-length	Sequential	Eight bytes per record.
Segmented	Sequential	Four bytes per record. One additional padding byte (space) is added if the specified record size is an odd number.
Stream	Sequential	None required.
Stream_CR	Sequential	One byte per record.
Stream_LF	Sequential	One byte per record.