EXTCOUNT enables special processing to accommodate applications that have record counts that exceed MFX’s default internal limit.
By default, the internal limit on the number of records that can be sorted for variable-length data or for a sort application that uses the EQUALS option is 4,294,967,295 records. Specifying EXTCOUNT increases the internal limit to 140,737,488,355,327 records. Fixed-length sorts without EQUALS, and all merges and copies, have automatic support for the maximum number of records allowed by the EXTCOUNT parameter.
Note that additional SORTWK space may be required when specifying the EXTCOUNT parameter with a VL sort or a fixed-length sort with EQUALS. The additional SORTWK space is 2 bytes per record. This amount can add a significant percentage to the SORTWK space needs if the LRECL of the records is small. (Small LRECLs are typical of files with an extremely large number of records). Therefore, when using EXTCOUNT with a VL sort or a fixed-length sort with EQUALS, insure that the extra SORTWK space will be available.
Performance will usually be improved if the EXTCOUNT option is not in effect. Therefore, EXTCOUNT should be used only when appropriate to the application.
If the record limit is exceeded, MFX will issue a critical error message and terminate the application.