SLDS input to warm start and emergency restart

SLDS input might be required to perform a warm start or emergency restart. When the SLDS is required for restart, IMS dynamically allocates it. IMS also deallocates any data sets previously allocated with the dynamic allocation macro (DFSMDA) with IMSLOGR or IMLOGR2 as the DD name for the TYPE=SLDS statement.

DBRC provides the data set name and volume information for the dynamically allocated SLDSs. However, DBRC does not provide the unit type information, so a DFSMDA member with the name of IMSLOGR must provide the unit type.

In some cases, you may want to force IMS to read from the SLDS instead of the OLDS during restart—for example, to prevent IMS from reading an OLDS that you know is invalid or has been corrupted. To force IMS to read from the SLDS, you need to delete the OLDS entry from the PRIOLDS and SECOLDS records in the RECON data set. To delete an OLDS entry from the RECON data set, use the DELETE.LOG OLDS(ddname) command, where ddname is the name of the primary OLDS.

Attention: When image copy, change accumulation, and log data sets are listed in the RECON status record as being under the control of a catalog management system (CA | IC | LOG DATA SETS CATALOGED=YES), the restart of IMS will fail if the SLDS data sets are not actually cataloged. The volume serial number (VOLSER) is not passed back to IMS for data set allocation when the data sets are not cataloged. Likewise, if the data sets are SMS-managed and not cataloged (CA | IC | LOG DATA SETS CATALOGED=NO), the restart of IMS might fail if SMS migrated the SLDS data sets to a different volume serial number. In this case, the volume serial number will be passed back to IMS but it does not match the volume serial number where the data set resides. Therefore, it is important to set the CATDS keyword on the CHANGE.RECON or INIT.RECON command correctly.