0S16I LOCK REQUEST MAY CAUSE A DEADLOCK

Products

• Scheduler VSE

Issue/Introduction

A batch job abends with message "0S16I LOCK REQUEST MAY CAUSE A DEADLOCK". 

We first opened a problem issue at IBM, and they asked to modify the jcl in order to get more error documentation. After the problem recurred, IBM analyzed the dump, and they detected: 

LockTab Entry showing Lockword DLBSLASL which is used by Label Service for access to label Area.

So this looks as if LOCK request from CA Scheduler conflicts with existing LOCK issued by JCL.

 

Environment

Release : 7.3

Component : Scheduler Job Management for z/VSE

Resolution

Does not look like a Scheduler issue.

The problem was within the JCL: forgot to use the statement // OPTION USRLABEL after having added a DLBL-card to the system standard label area (via // OPTION STDLABEL=ADD), and this could sometimes lead to the situation that a lock for the DLA-file was not ended.

The correct jcl is for this sample is:

... // OPTION STDLABEL=ADD                           // TLBL KTOZUS,'M.KTOZUS,Z,H,DL',,,,,1   /*                                               // OPTION USRLABEL                               /*                                               ...