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.
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. |