Threadsafe Considerations

Since Natural is fully reentrant, Natural CICS Interface can be defined as threadsafe by using the CICS CONCURRENCY(REQUIRED) attribute. Natural CICS Interface can then execute in the CICS open transaction environment (OTE) under an open TCB to reduce the QR CPU constraint by moving tasks to other processors. Natural CICS Interface provides for extra serialization using CICS ENQ/DEQ when running under an open TCB.

To minimize these serialization efforts, it is required:


  1. All user programs defined as CSTATIC have to be threadsafe.
  2. All dynamic user programs which are invoked via standard linkage conventions either explicitly (that is, using the terminal command %P=S, %P=SC, *P=L or %P=LS, or the PGP profile parameter with the respective property) or implicitly (that is, when the NCIPARM generation parameter SLCALL is set to YES) have to be threadsafe. Additional information on threadsafe programs can be found in the IBM documentation related to CICS application programming.