Restart Data Sets

Restart data sets are similar to disjoint standard data sets that have no variable-format records. (Refer to “Standard Data Set (Fixed Format)” and “Standard Data Set (Variable Format)” later in this appendix for more information on standard data sets.)

The first word of every restart data set record is a TRANSACTION COUNT item. This is a count of the number of times the program has been in transaction state. The counter is initialized to 0 (zero) and incremented at ENDTRANSACTION time after the restart area has been saved in the audit trail.

A RESTART TYPE item is located in the first digit of the second word of every restart data set record. The RESTART TYPE item identifies the value of the restart record. The RESTART TYPE item occupies two digits, although only the first is used.

The TRANSACTION COUNT and RESTART TYPE items are present in every restart data set record regardless of whether they are explicitly declared or not. These items must be explicitly declared in the DASDL description if a user program is to access them.

When a database uses the EXTENDED attribute, the last record of the restart data set contains a Transtamp in word 4.

If a database is audited, then you must include a restart data set in the database definition. In addition, any logical databases included in the database definition must also refer to the restart data set.

Example

The following example illustrates the DASDL syntax for a restart data set: 

RDS         RESTART DATA SET
(
            TC    TRANSACTION COUNT;
            RT    RESTART TYPE;
            : 
            : 
            : 
);

Abort and halt/load recovery store records in the restart data set automatically. User programs can explicitly store records of types 0 through 6. The FIND NEXT operation skips records whose restart types are greater than 6.

Restart Record Types

Restart Record Types explains the numbers associated with the different types of restart records.

Table 73. Restart Record Types

Type

Description

0

The record is stored by the user.

1

The last good restart area for a BEGIN-TRANSACTION operation. The record is stored by the RECOVERY process.

2

The last good restart area for an END-TRANSACTION operation. The record is stored by the RECOVERY process.

3

The last good restart area for a BEGIN-TRANSACTION operation. The record is stored during a CLOSE procedure if the program is discontinued.

4

The last good restart area for an END-TRANSACTION operation. The record is stored during a CLOSE procedure if the program is discontinued.

5 and 6

The record is stored by the user.

7 through 14

These records are not used.

15

Available record slot.

For restart data sets, the whole of block 0 is unused.

Restart Data Set Restrictions

following restrictions apply to restart data sets:

  • One restart data set must be declared for each audited database.

  • Links and embedded data sets are not allowed.

  • Restart data sets must not be embedded.

  • Variable-format records are not permitted.

  • No links can reference the restart data set.

  • The restart data set cannot be used in a remap.

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