The DCBD macro generates a dummy control section that provides symbolic names for the fields in one or more data control blocks. The DCBD macro maps the assembler version of the DCB. Symbols generated by the DCBD macro include some that are not part of the intended programming interface. The names and attributes of the general-use fields appear as part of the description of each data control block in Data control block symbolic field names. Attributes of the symbolically named fields in the dummy section are the same as the fields in the data control blocks, except for fields containing 3-byte addresses. The symbolically named fields containing 3-byte addresses have length attributes of 4 and are aligned on fullword boundaries.

The symbols generated by the DCBD macro should not be defined in your user program. The symbols are structured as DCBxxxxx, where DCB is the first 3 characters and xxxxx is one or more alphanumeric characters.

The name of the dummy control section generated by a DCBD macro is IHADCB. A USING instruction specifying IHADCB and a dummy section base register must precede the symbolic names in the dummy section. The dummy section base register contains the address of the actual data control block. You can issue the DCBD macro only once in any assembled module. However, you can use the resulting symbolic names for any number of data control blocks by changing the address in the dummy section base register. You can code the DCBD macro at any point in a control section. However, if it is coded at any point other than at the end of a control section, you must code a CSECT instruction to resume the control section.

The format of the DCBD macro is:

DSORG=({GS|(dsorglist)})

specifies the types of data control blocks for which symbolic names are provided. If the DSORG parameter is omitted, the DEVD parameter is ignored, and symbolic names are provided only for the 'foundation block' portion that is common to all data control blocks.

GS

specifies a data control block for graphics. This parameter cannot be used in combination with any of the below.

dsorglist

You can specify one or more of the following values (each value must be separated by a comma):

BS

specifies a data control block for BSAM.

DA

specifies a data control block for BDAM. Although this option is supported, its use is not recommended.

IS

specifies a data control block for BISAM and QISAM. Although this option is supported, its use is not recommended.

LR

specifies a dummy section for the logical record length field (DCBLRECL) only.

PO

specifies a data control block for BPAM.

PS

specifies a data control block for BSAM and QSAM. PS includes both BS and QS.

QS

specifies a data control block for QSAM.

DEVD=(devlist)

specifies the types of devices on which the data set can reside. If DEVD is omitted and BS, QS, or PS is specified in DSORG, symbolic names are provided for all the device types listed below.

devlist

You can specify one or more of the following values (each value must be separated by a comma). If you specify more than one value, they must have parentheses around them.

DA

Direct access storage device

PC

Directly-allocated card punch (not SYSOUT)

PR

Directly-allocated printer (not SYSOUT)

RD

Directly-allocated card reader or read punch feed (not spooled)

TA

Magnetic tape

MR

Magnetic character reader