The most likely reason is that your Easysoft Data Access (EDA) for Zortec System Z locking mode is incorrect. Try changing it by running the following script, which is installed on the server:
cd /usr/local/easysoft/isam/lib ./disam_select.sh
The output is:
Disam Locking Mode Selection ** NOTE : All locking modes may not be available on all platforms ** 1. Disam 96 (ISLOCKING = 1 C7LOCKING = 0) (cisam pre 4.1) 2. Disam 96 (ISLOCKING = 2 C7LOCKING = 0) (cisam pre 5.0) 3. Disam 96 (ISLOCKING = 2 C7LOCKING = 1) (cisam 5.0 > 7.1) [default] 4. Disam 96 (ISLOCKING = 2 C7LOCKING = 2) (cisam 7.2) 5. Disam 96 (ISLOCKING = 2 C7LOCKING = 2) (cisam 7.26) Select required locking mode? (1-5) [3]:
If you don't know what version of C-ISAM you're running, cycle through all versions. One of them will set the locking mode correctly. EDA for Zortec System Z supports locking modes for all versions of C-ISAM.