bdfp1m11Programming Concepts and Reference

dfckp-Checkpoint a Subfile

Use this function to checkpoint a subfile; that is, all blocks in main storage that have been changed are copied to DASD.

Format

dft_rec *dfckp(dft_fil *file, dft_opt options);



file
is a pointer to the base address of the SW00SR slot (defined in c$sw00sr.h) of the subfile that you want to access and is returned by the dfopn function.

options
are the processing options for this function. Use one of the following values:

DFCKP_DETAC
places the subfile in detac mode after checkpointing the subfile. When the subfile is in detac mode, all modified blocks are saved in main storage. Any changes that you make to the LRECs in that subfile are not written to DASD until the subfile is checkpointed or closed. You can discard modified LRECs (prevent them from being written to DASD) by using the DFCLS_ABORT value on the options parameter of the dfcls function.
Note:
The TPF system and the ALCS environment issues a 000010 system error if an application program does not give up control in the time allotted by the application time-out counter. When processing in detac mode, a TPFDF application program can require more than the allotted time on a database with a large data structure. To prevent the 000010 system error, you can change the setting of the &TPFDBDV symbol in the DBLCL macro.

See TPFDF Installation and Customization for more information about the &TPFDBDV symbol and the DBLCL macro.

DFCKP_NODET
specifies that you do not want the subfile in detac mode after it has been checkpointed.

DFCKP_TM
specifies that commit scopes are used during checkpoint processing, regardless of what the database definition (DBDEF) macro has set as the default. This option is valuable when you want to file out many files during checkpoint processing (for example, detac mode, extensive B+Tree indexing updates, and requests that result in packing).

DFCKP_NO_TM
specifies that commit scopes are not used during checkpoint processing, regardless of what the DBDEF macro has set as the default.

0
specifies that you do not want to use any processing options.

Entry Requirements

None.

Normal Return

The subfile remains open and the current logical record (LREC) remains the same.

Error Return

 See Identifying Return Indicators and Errors for information about how to check the error indicators. 

Programming Considerations

Examples

Related Functions