This blog contains experience gained over the years of implementing (and de-implementing) large scale IT applications/software.


A background job has produced a short dump with SYSTEM_NO_TASK_STORAGE.
The “Heap Memory” section in ST02 showed a maximum use of 1.5GB, but we had allocated nearly 1.9GB according to the “abap/heap_area_nondia” and “abap/heap_area_dia” instance profile parameters.

The ST02 short dump analysis shows the source code line where the problem occurred. The line of code doesn’t look specifically interesting, it is, however, requiring a slight increase in memory allocation.
If the program is running in DIALOG then it will be allocated Extended Memory first, followed by HEAP (local process) memory.
If the program is running in BACKGROUND then it will be allocated HEAP memory first, followed by Extended Memory.

Extended Memory is pre-allocated at system startup according to the EM initial setting in the SAP instance profile.  It is then increased up to the maximum specified in the instance profile per user and per application server.
HEAP memory is only allocated as it is needed within each of the SAP dw.* OS processes, up to the maximum specified (in instance profile) per user or per application server.  It is then released back to the OS when the process finishes processing (SAP restarts the work process) and it has used over a specific amount of memory as set in parameter abap/heaplimit.

Since this was a background job, we can assume that we exhausted HEAP memory and should have automatically switched to Extended Memory.
However, the Kernel section of the short dump showed that we may have experienced an issue obtaining more virtual memory from the OS:

*** Error in libunwind: Out of memory. Try with a higher value >
 > for UNWIND_RESERVE_MEM (current value = 16).
 (0) 0x40000000017ae480 [dw.sapXXX_DVEBMGS01]
 (1) 0x40000000017ae2b0 [dw.sapXXX_DVEBMGS01]
 (2) 0x40000000021de880 [dw.sapXXX_DVEBMGS01]
 (3) 0x40000000021e45d0 [dw.sapXXX_DVEBMGS01]
 (4) 0x400000000115e860 [dw.sapXXX_DVEBMGS01]
 (5) 0x400000000120b3a0 [dw.sapXXX_DVEBMGS01]
 (6) 0x40000000010542f0 [dw.sapXXX_DVEBMGS01]
 (7) 0x4000000001111940 [dw.sapXXX_DVEBMGS01]
 (8) 0x40000000011ae790 [dw.sapXXX_DVEBMGS01]
 (9) 0x40000000012fb090 [dw.sapXXX_DVEBMGS01]
 (10) 0x40000000012fd7d0 [dw.sapXXX_DVEBMGS01]
 (11) 0x400000000188cae0 [dw.sapXXX_DVEBMGS01]
 (12) 0x4000000001896e70 [dw.sapXXX_DVEBMGS01]
 (13) 0x4000000001891670 [dw.sapXXX_DVEBMGS01]
 (14) 0x40000000018949a0 [dw.sapXXX_DVEBMGS01]
 (15) 0x400000000187f1e0 [dw.sapXXX_DVEBMGS01]
 (16) 0x40000000014d1ce0 [dw.sapXXX_DVEBMGS01]
 (17) 0x400000000149e8d0 [dw.sapXXX_DVEBMGS01]
 (18) 0x4000000001496fc0 [dw.sapXXX_DVEBMGS01]
 (19) 0x4000000001364c30 [dw.sapXXX_DVEBMGS01]
 (20) 0x4000000000ed4af0 [dw.sapXXX_DVEBMGS01]
 (21) 0x4000000000ed4a90 [dw.sapXXX_DVEBMGS01]
 (22) 0xc000000000045880 main_opd_entry + 0x50 [/usr/lib/hpux64/]

Is this case, you could either add more OS memory (essentially you have over allocated memory somewhere), or you could resize the abap/heap_area_nondia parameter to a smaller amount, so that it will switch to EM sooner.