What is the maximum IDMS queue record length based on?

Products

• IDMS
• IDMS - Database
• IDMS - ADS

Issue/Introduction

What is the maximum queue record length? Is it related to the page size of DDLDCRUN area?

 

Environment

IDMS - All Supported releases

Resolution

There is no documented limit on the size of a queue record. When a queue record is written a QUEUE-DCQ-138 header record is written if the Queue does not already exist and an SROOT-DCS-139 record is created to contain the Queue data. If the queue record is less than 500 bytes it will fit entirely in that record occurrence. If the queue record is greater than 500 bytes the first 500 go into the SROOT-DCS-139 record and the remaining length is spread across one or more SEXT-DCS-140 records. Each SEXT-DCS-140 record can hold up to 500 bytes. The SROOT-DCS-139 owns the SEXT-DCS-140 record through a standard chained set so the number of members is unlimited so the length of the record from a DB standpoint is unlimited. 

Of course there may be practical limits such as the amount of space one can allocate and use within the program language used to access the queue. A GET QUEUE can return the length in a user-defined field. The DML Reference guides say the field the length is returned into is a 4 byte field so the possible number could be rather large.

Information on SROOT-DCS-139 and SEXT-DCS-140 can be located in the IDMS Dictionary Structure Reference