ISITMGD completion codes

When the system returns control to your problem program, the low-order byte of register 15 contains a return code. The low-order byte of register 0 contains a reason code.

The ISITMGD return and reason codes are as follows:

Return Code (15)	Reason Code (0)	Meaning
00 (X'00')		Successful completion.
04 (X'04')	04 (X'04')	Data control block was not open.
04 (X'04')	08 (X'08')	Data extent block was not valid.
04 (X'04')	16 (X'10')	An access method control block (ACB), not a DCB, was supplied.
04 (X'04')	20 (X'14')	DEB extension does not exist.
04 (X'04')	28 (X'1C')	Access method type is not supported.
04 (X'04')	32 (X'20')	Invalid unit control block (UCB).
04 (X'04')	36 (X'24')	Invalid SMS control block.
04 (X'04')	40 (X'28')	Invalid SMS control block. This could be caused by a bad DCB, a DEB error, or an internal SMS error.
04 (X'04')	48 (X'30')	Invalid INOUT DCB or DEB address. The input DCB and DEB control blocks did not point to each other.
04 (X'04')	52 (X'34')	DEBCHK error.
08 (X'08')	00 (X'00')	ISITMGD macro is not supported on current level of system. Must be MVS/DFP 3.2 or later.
12 (X'0C')	00 (X'00')	Reserve bits in the parameter list are set on, possibly function requested which is not supported on this level of ISITMGD.
12 (X'0C')	04 (X'04')	Invalid parameter list pointer.
12 (X'0C')	08 (X'08')	Invalid parameter list level.
12 (X'0C')	12 (X'0C')	Invalid parameter list length.
12 (X'0C')	16 (X'10')	Invalid concatenation number.
12 (X'0C')	20 (X'14')	Invalid concatenation number.
12 (X'0C')	24 (X'18')	DCB or DEB pointer is zero.
12 (X'0C')	28 (X'1C')	The bits indicating the DCB and DEB are either both on or off. Either both the DCB and DEB were supplied or neither.
16 (X'10')	04 (X'04')	Data type not set due to SMS error, dump taken.
16 (X'10')	08 (X'08')	Data type not set due to SMS error, no dump taken.