DDESCR Control Block Format

The DGA$DDSR member of the $CD.SDGAMAC library lists the DDESCR control block format. You can modify the control block fields listed in the following table. Do NOT modify any displacement fields listed in the member.

Note: Turning a flag on means setting the bit in the byte where the flag is located to one. Turning a flag off means setting the bit in the byte where the flag is located to a zero.
Attention:

Do not modify the fields D1DMEMB, D1DDSN, and D1DVOLN. These fields represent displacements to their corresponding values. However, after calculating the address of the values (by adding the displacement to the address of the TCQSH) IBM® Connect:Direct® can change the actual values. At the calculated address, you will find a halfword field representing the length of the data that follows. If you change the length of the data, you must also change this halfword to reflect the new length. If the displacement to one of these fields is 0, do not insert a value or displacement. For example, if D1DMEMB=0, no member name was specified and a member name cannot be inserted. Do not set on the D1MEMNAM flag if D1DMEMB=0.

The same applies to D1DDSN. For D1DVOLN, if the displacement is 0, you cannot modify this field or turn on the D1DVOLSER flag. Also, you cannot add volume serial numbers to this list. You can delete volume serial numbers from the list or change the volume serial number. If volume serial numbers are deleted, decrement the length field by 6 for each one deleted. If all volume serial numbers are deleted, make D1DVOLN=0 and turn off the D1VOLSER bit.

Field Explanation Use Instructions
D1DTYPE entry in the IBM Connect:Direct type defaults file N/A
D1BLKSIZ block size To use the block size in the destination data set description portion of the copy control block, set D1BLKSZE flag on. To use the block size in the Type record, set the D1BLKSZE flag off.
D1DEN tape density To use the tape density indicated in the destination data set portion of the Copy control block, set the D1DENSTY flag on.
D1DSORG data set organization To use this value, set the D1DSORGN flag on. To use the value indicated in the type record, set the D1DSORGN flag off.
D1LRECL logical record length To use this value, set the D1LRECLN flag on. To use the value indicated in the type record, set the D1LRECLN flag off.
D1RECFM record format To use this value, set the D1RECFMT flag on. To use the value indicated in the type record, set the D1RECFMT flag off.
D1RKP relative key position To use this value, set the D1RKYP flag on.
D1TRTCH 7-track recording mode To use this value, set the D1TRKTCH flag on.
D1LABTYP label type To use this value, set the D1LABEL flag on.
D1RETPD retention period To use this value, set the D1RETPRD flag on. To use the value indicated in the D1EXPDT field, set the D1RETPRD flag off.
D1EXPDT retention period To use this value, set the D1EXPDTE flag on.
D1PRILOC primary allocation amount All of the following bits must be set off to use the space allocation values specified in the type record: D1TRK, D1CYL, D1BLK.
D1SECLOC secondary allocation amount To use this value, set the D1SECALL flag on. Set all of the following bits to off to use the space allocation values specified in the type record: D1TRK, D1CYL, D1BLK.
D1DIRBLK number of directory blocks To use this value, set the D1DIRBLK flag on. Set all of the following bits to off to use the space allocation values specified in the type record: D1TRK, D1CYL, D1BLK.
D1UNIT unit type or group name To use this value, set the D1GRPTYP flag on. To use the value indicated in the type record, set the D1GRPTYP off. Set all of the following bits to off to use the UNIT value specified in the type record: D1UNCNT, D1P, D1DEFER, D1GRPTYP.
D1VOLSEQ volume sequence number To use this value, set the D1VOLSQ flag on.
D1VOLCT volume count To use this value, set the D1VOLCNT flag on.
D1PASSWD data set password To use this value, set the D1PWD flag on.
D1DMEMB displacement to the member name field† N/A
D1DDSN displacement to the data set name field† N/A
D1DVOLN displacement to the volume serial number† N/A
† See the Caution that precedes this table.