Initially TM (transactional memory) support was added to CLQ (ConcurrenLinkedQueue) and CHM (ConcurrentHashMap). However, further testing didn't show significant improvements with CHM, and changes for CHM were not added to IBM java 8, however CLQ is manintained in IBM Java 8.
This was discussed under the following Slack archive -
https://ibm-cloud.slack.com/archives/C401VJBD2/p1539375869000100
Summary of discussion - ::
It's ~100 lines of fairly straightforward code in the JIT and probably <= 20 lines of code in the JCL. In other words the "cost" of maintaining CLQ is not that much.
This issue is to add TM support for CLQ in the ibmruntimes extension repo.