| 摘要 |
PURPOSE:To retrieve data at the high speed by storing both DSCB4 and DSCB5 into the head track of a VTOC, detecting only the track serving as a subject of the data set name and furthermore preparing an overflow track area. CONSTITUTION:A VTOC is divided into a control area 1, a control area 2 and an overflow track area 3. The head track of the VTOC is allocated to the area 1 and contains a DSCB4 and a DSCB5. While plural tracks are allocated to to the area 2 and store the DSCB1-3. A specific track that stores the DSCB1 against a certain data set is decided by dividing a data set name by the number of tracks of the area 2 and defining the residue as the corresponding track number. In case the relevant track has an overflow, the corresponding DSCB is stored in the area 3. In such a way, data can be retrieved at a high speed.
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