DYNAMIC_EXTEND on Datacom areas without secondary space allocation

Products

• Datacom

Issue/Introduction

Datacom system (CXX, LXX) or database (index, data) areas have been allocated without setting a secondary space value, for example:

//LXX      DD DSN=CAI.NEWHLQ.9CXX_NAME.LXX,
//         SPACE=(CYL,(150)),             
//         UNIT=&BDUNI1,                   
//         &VOL1,                          
//         DISP=(NEW,CATLG,DELETE)         

Is it possible to run a DYNAMIC_EXTEND console command, for example:

/F mufjobname,DYNAMIC_EXTEND 0,LXX,50,CYL

to increase the size of these files?

Environment

Datacom 15.1 and above on z/OS

Resolution

Yes, the DYNAMIC_EXTEND command works even if the dataset has been allocated without setting a secondary space value.

Additional Information

This extend process (called direct extend) is started on-demand by user and is different from the automatic dynamic extend driven directly by the MUF.

The on-demand process overrides the current secondary extent size by design for any system (CXX and LXX) or database area (index and data), so either undersized secondary extent or no extent at all.   

For details about DYNAMIC_EXTEND command, please carefully read How to extend a Datacom area while the database is open article.