BSAM, BPAM interface

Offset	Bytes in Length	Field Name	Description
61(3D)	1	DCBCIND2	Condition indicators.
		.... .1..	DCBCNCHS. Chain scheduling being supported. Set in OPEN. Zero for DASD. May differ from OPTCD=C bit(DCBOPTC).
72(48)	1	DCBNCP	Number of channel programs. Number of READ or WRITE requests that can be issued before a CHECK. Maximum number: 255.
80(50)	1	DCBUSASI/ DCBLBP	ASCII tape. Block prefix.
		.1.. ....	Block prefix is a 4-byte field containing the block length.
81(51)	1	DCBBUFOF	Block prefix length.
82(52)	2	DCBLRECL	Logical record length. For fixed-length blocked record format, the presence of DCBLRECL allows BSAM to read truncated records. For undefined records, this field contains block size.