What is Control Interval, Control Area ?

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What is Control Interval, Control Area ?

Control Interval is analogous to a physical block for QSAM files. It is the unit of I/O. Must be between 512 bytes to 32 k. Usually either 2K or 4K. A larger control interval increases performance for sequential processing while the reverse is true for random access. Under CICS when a record is locked, the entire CI gets locked.
Control Area is a group of control intervals. CA is used during allocation. CA size is calculated based on the allocation type (cyl, tracks or records ) and can be max of 1 cylinder.

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Other Job Interview Questions

• What is FREESPACE ?
• Name some common VSAM error conditions and codes.
• What is the VSAM-code field ?
• Is a delete operation possible in an ESDS ? B, is rewrite operation possible in ESDS ?
• How do you initialize a VSAM file before any operation ? a VSAM with alternate index ?
• What does a file status of 02 on a VSAM indicate ?
• What is a VSAM slot ?
• How are records stored in an ESDS, entry sequenced dataset?
• How do you define an ALTINDX ? How do you use ALTINDXs in batch, CICS program's ?
• How do you fix the problem associated with VSAM out of space condition ?
• More...